API: Add compression argument to Series.to_csv
- [ ] closes #18958
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

Hello @reidy-p! Thanks for updating the PR.







Cheers ! There are no PEP8 issues in this Pull Request. :beers: 

##### Comment last updated on January 14, 2018 at 23:47 Hours UTC # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19216?src=pr&el=h1) Report
> Merging [#19216](https://codecov.io/gh/pandas-dev/pandas/pull/19216?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/787ab5556f23d2e10b798d2e58e66789d79fd4d5?src=pr&el=desc) will **decrease** coverage by `0.03%`.
> The diff coverage is `86.66%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/19216/graphs/tree.svg?token=eZ4WkYLtcO&src=pr&height=150&width=650)](https://codecov.io/gh/pandas-dev/pandas/pull/19216?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #19216      +/-   ##
==========================================
- Coverage   91.55%   91.52%   -0.04%     
==========================================
  Files         147      147              
  Lines       48812    48827      +15     
==========================================
- Hits        44690    44689       -1     
- Misses       4122     4138      +16
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.89% <86.66%> (-0.03%)` | :arrow_down: |
| #single | `41.69% <6.66%> (-0.02%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/19216?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/series.py](https://codecov.io/gh/pandas-dev/pandas/pull/19216/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc2VyaWVzLnB5) | `94.61% <ø> (ø)` | :arrow_up: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/19216/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `84.24% <86.66%> (-0.18%)` | :arrow_down: |
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/19216/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `65.22% <0%> (-1.74%)` | :arrow_down: |

------

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> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19216?src=pr&el=footer). Last update [787ab55...33a90dc](https://codecov.io/gh/pandas-dev/pandas/pull/19216?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 @jreback did you post comments? I can't see any. sorry, see #19226 want to parametrize these tests @jreback @reidy-p : I like the `decompress` utility (it should be applied to our `DataFrame.to_csv` tests), but this patch for `Series.to_csv` is only a band-aid.  We should really implement what you summarized in your comment <a href="https://github.com/pandas-dev/pandas/issues/18958#issuecomment-357449553">here</a> to close this issue. @gfyoung I agree, but it puts this in a central location at least for now. thanks @reidy-p ok would love to work on centralizing the compression tests!