[REF] Move remaining locale functions to _config.localization
There are a a couple locale-centric functions left in `tm` that have not yet been moved because they depend on `pd.options.display.encoding`.  This PR implements a minimal `_config.display` that allows us to consolidate the locale functions.  `_config.display` also defines `display.date_dayfirst` and `display.date_yearfirst`, since those are used by `tslibs.parsing`.  So this completes the process of removing `tslib`'s dependency on `core`.

The existing `get_locales` function has a `if PY3` check that is no longer necessary, so this removes the PY2 branch of that.
Hello @jbrockmendel! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:



















There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2019-03-25 13:55:53 UTC # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25861?src=pr&el=h1) Report
> Merging [#25861](https://codecov.io/gh/pandas-dev/pandas/pull/25861?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/2618b218eb4fad936310dcce011acc1b79e0ed96?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `89.09%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25861/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25861?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #25861      +/-   ##
==========================================
+ Coverage   91.47%   91.47%   +<.01%     
==========================================
  Files         173      174       +1     
  Lines       52872    52876       +4     
==========================================
+ Hits        48364    48369       +5     
+ Misses       4508     4507       -1
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.04% <89.09%> (ø)` | :arrow_up: |
| #single | `41.83% <70.9%> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25861?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/25861/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `89.74% <ø> (+0.43%)` | :arrow_up: |
| [pandas/io/formats/console.py](https://codecov.io/gh/pandas-dev/pandas/pull/25861/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2Zvcm1hdHMvY29uc29sZS5weQ==) | `79.41% <ø> (-6.87%)` | :arrow_down: |
| [pandas/core/config\_init.py](https://codecov.io/gh/pandas-dev/pandas/pull/25861/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvY29uZmlnX2luaXQucHk=) | `99.2% <ø> (-0.05%)` | :arrow_down: |
| [pandas/\_config/\_\_init\_\_.py](https://codecov.io/gh/pandas-dev/pandas/pull/25861/diff?src=pr&el=tree#diff-cGFuZGFzL19jb25maWcvX19pbml0X18ucHk=) | `100% <100%> (ø)` | :arrow_up: |
| [pandas/\_config/display.py](https://codecov.io/gh/pandas-dev/pandas/pull/25861/diff?src=pr&el=tree#diff-cGFuZGFzL19jb25maWcvZGlzcGxheS5weQ==) | `100% <100%> (ø)` | |
| [pandas/\_config/localization.py](https://codecov.io/gh/pandas-dev/pandas/pull/25861/diff?src=pr&el=tree#diff-cGFuZGFzL19jb25maWcvbG9jYWxpemF0aW9uLnB5) | `86% <76.92%> (-9.84%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25861?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/25861?src=pr&el=footer). Last update [2618b21...1bb6dfd](https://codecov.io/gh/pandas-dev/pandas/pull/25861?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25861?src=pr&el=h1) Report
> Merging [#25861](https://codecov.io/gh/pandas-dev/pandas/pull/25861?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/d8642e903cccb8fa0ea4d4477c89bbc1523b8c8e?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `89.65%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25861/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25861?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #25861      +/-   ##
==========================================
+ Coverage   91.47%   91.48%   +<.01%     
==========================================
  Files         173      175       +2     
  Lines       52872    52877       +5     
==========================================
+ Hits        48367    48372       +5     
  Misses       4505     4505
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.04% <89.65%> (ø)` | :arrow_up: |
| #single | `41.82% <72.41%> (+0.01%)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25861?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/25861/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `89.74% <ø> (+0.33%)` | :arrow_up: |
| [pandas/io/formats/console.py](https://codecov.io/gh/pandas-dev/pandas/pull/25861/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2Zvcm1hdHMvY29uc29sZS5weQ==) | `78.12% <ø> (-8.15%)` | :arrow_down: |
| [pandas/core/config\_init.py](https://codecov.io/gh/pandas-dev/pandas/pull/25861/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvY29uZmlnX2luaXQucHk=) | `99.2% <ø> (-0.05%)` | :arrow_down: |
| [pandas/\_config/\_\_init\_\_.py](https://codecov.io/gh/pandas-dev/pandas/pull/25861/diff?src=pr&el=tree#diff-cGFuZGFzL19jb25maWcvX19pbml0X18ucHk=) | `100% <100%> (ø)` | :arrow_up: |
| [pandas/\_config/display.py](https://codecov.io/gh/pandas-dev/pandas/pull/25861/diff?src=pr&el=tree#diff-cGFuZGFzL19jb25maWcvZGlzcGxheS5weQ==) | `100% <100%> (ø)` | |
| [pandas/\_config/dates.py](https://codecov.io/gh/pandas-dev/pandas/pull/25861/diff?src=pr&el=tree#diff-cGFuZGFzL19jb25maWcvZGF0ZXMucHk=) | `100% <100%> (ø)` | |
| [pandas/\_config/localization.py](https://codecov.io/gh/pandas-dev/pandas/pull/25861/diff?src=pr&el=tree#diff-cGFuZGFzL19jb25maWcvbG9jYWxpemF0aW9uLnB5) | `86% <76.92%> (-9.84%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25861?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/25861?src=pr&el=footer). Last update [d8642e9...f06c21a](https://codecov.io/gh/pandas-dev/pandas/pull/25861?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks @jbrockmendel 