Fix import format at pandas/tests/io/parser directory
- [x] partial #23334
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`

Ran `isort --recursive pandas/tests/io/parser` and then checked imports using `isort --recursive --check-only pandas/tests/io/parser`

This PR also exceeded 20 file limit (22 files with setup.cfg), but I think it's acceptable and unnecessary to divide it to two separate PRs.


Hello @mwoss! Thanks for submitting the PR.

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/c_parser_only.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/c_parser_only.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/comment.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/comment.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/common.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/common.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/compression.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/compression.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/converters.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/converters.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/dialect.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/dialect.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/dtypes.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/dtypes.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/header.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/header.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/index_col.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/index_col.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/mangle_dupes.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/mangle_dupes.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/multithread.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/multithread.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/na_values.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/na_values.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/parse_dates.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/parse_dates.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/python_parser_only.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/python_parser_only.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/quoting.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/quoting.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/skiprows.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/skiprows.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/test_network.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/test_network.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/test_parsers.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/test_parsers.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/test_read_fwf.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/test_read_fwf.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/test_textreader.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/test_textreader.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/test_unsupported.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/test_unsupported.py) !

 - There are no PEP8 issues in the file [`pandas/tests/io/parser/usecols.py`](https://github.com/mwoss/pandas/blob/8ac1578f3b83ce012651682354c03ebbf8cc6e88/pandas/tests/io/parser/usecols.py) !

 Tests failed due to:
> The job exceeded the maximum time limit for jobs, and has been terminated.

Should I commit something to trigger build again? Restarted the Travis job. Didn't see an option in Azure - @TomAugspurger can you help here? Am I overlooking in the UI or do I need to get something squared away with access? Was assuming I'd be able to do it as follows:

<img width="848" alt="image" src="https://user-images.githubusercontent.com/609873/47595454-5f4a5080-d935-11e8-8e66-b4427941cbcf.png">
 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23367?src=pr&el=h1) Report
> Merging [#23367](https://codecov.io/gh/pandas-dev/pandas/pull/23367?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/caea25a8b91d62b30eef99aa0c523448e19cd6db?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/23367/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/23367?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #23367   +/-   ##
=======================================
  Coverage   92.22%   92.22%           
=======================================
  Files         169      169           
  Lines       51261    51261           
=======================================
  Hits        47277    47277           
  Misses       3984     3984
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.66% <ø> (ø)` | :arrow_up: |
| #single | `42.23% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23367?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23367?src=pr&el=footer). Last update [caea25a...8ac1578](https://codecov.io/gh/pandas-dev/pandas/pull/23367?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks @mwoss 