Fixes timezone drop when encoding it in msgpack
- [x] closes #25148
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

***After***

```python
In [1]: import numpy as np
   ...: import pandas as pd
   ...:
   ...: idx = pd.date_range(start='2018-12-02 14:50:00-07:00', end='2018-12-03 03:11:00-07:00', freq='1min')
   ...:
   ...:
   ...: df = pd.DataFrame(np.random.randn(len(idx), 1), index=idx, columns=['A'])

In [2]: df.index[0]
Out[2]: Timestamp('2018-12-02 14:50:00-0700', tz='pytz.FixedOffset(-420)', freq='T')

In [3]: df.to_msgpack('~/foo.msgpack')

In [4]: df = pd.read_msgpack('~/foo.msgpack')

In [5]: df.index[0]
Out[5]: Timestamp('2018-12-02 14:50:00-0700', tz='pytz.FixedOffset(-420)', freq='T')
```
Hello @cgangwar11! Thanks for updating the PR.





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

##### Comment last updated on February 09, 2019 at 18:27 Hours UTC # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25195?src=pr&el=h1) Report
> Merging [#25195](https://codecov.io/gh/pandas-dev/pandas/pull/25195?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/638ddebaa7da1e569836a5b89593b120dbbf491c?src=pr&el=desc) will **decrease** coverage by `49.5%`.
> The diff coverage is `33.33%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25195/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25195?src=pr&el=tree)

```diff
@@             Coverage Diff             @@
##           master   #25195       +/-   ##
===========================================
- Coverage   92.35%   42.84%   -49.51%     
===========================================
  Files         166      166               
  Lines       52314    52315        +1     
===========================================
- Hits        48312    22414    -25898     
- Misses       4002    29901    +25899
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `?` | |
| #single | `42.84% <33.33%> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25195?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/packers.py](https://codecov.io/gh/pandas-dev/pandas/pull/25195/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3BhY2tlcnMucHk=) | `14.89% <33.33%> (-73.32%)` | :arrow_down: |
| [pandas/io/formats/latex.py](https://codecov.io/gh/pandas-dev/pandas/pull/25195/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2Zvcm1hdHMvbGF0ZXgucHk=) | `0% <0%> (-100%)` | :arrow_down: |
| [pandas/core/categorical.py](https://codecov.io/gh/pandas-dev/pandas/pull/25195/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvY2F0ZWdvcmljYWwucHk=) | `0% <0%> (-100%)` | :arrow_down: |
| [pandas/io/sas/sas\_constants.py](https://codecov.io/gh/pandas-dev/pandas/pull/25195/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3Nhcy9zYXNfY29uc3RhbnRzLnB5) | `0% <0%> (-100%)` | :arrow_down: |
| [pandas/tseries/plotting.py](https://codecov.io/gh/pandas-dev/pandas/pull/25195/diff?src=pr&el=tree#diff-cGFuZGFzL3RzZXJpZXMvcGxvdHRpbmcucHk=) | `0% <0%> (-100%)` | :arrow_down: |
| [pandas/tseries/converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/25195/diff?src=pr&el=tree#diff-cGFuZGFzL3RzZXJpZXMvY29udmVydGVyLnB5) | `0% <0%> (-100%)` | :arrow_down: |
| [pandas/io/formats/html.py](https://codecov.io/gh/pandas-dev/pandas/pull/25195/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2Zvcm1hdHMvaHRtbC5weQ==) | `0% <0%> (-99.35%)` | :arrow_down: |
| [pandas/core/groupby/categorical.py](https://codecov.io/gh/pandas-dev/pandas/pull/25195/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ3JvdXBieS9jYXRlZ29yaWNhbC5weQ==) | `0% <0%> (-95.46%)` | :arrow_down: |
| [pandas/io/sas/sas7bdat.py](https://codecov.io/gh/pandas-dev/pandas/pull/25195/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3Nhcy9zYXM3YmRhdC5weQ==) | `0% <0%> (-91.17%)` | :arrow_down: |
| [pandas/io/sas/sas\_xport.py](https://codecov.io/gh/pandas-dev/pandas/pull/25195/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3Nhcy9zYXNfeHBvcnQucHk=) | `0% <0%> (-90.15%)` | :arrow_down: |
| ... and [124 more](https://codecov.io/gh/pandas-dev/pandas/pull/25195/diff?src=pr&el=tree-more) | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25195?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/25195?src=pr&el=footer). Last update [638ddeb...99cab5a](https://codecov.io/gh/pandas-dev/pandas/pull/25195?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/25195?src=pr&el=h1) Report
> :exclamation: No coverage uploaded for pull request base (`master@2448e52`). [Click here to learn what that means](https://docs.codecov.io/docs/error-reference#section-missing-base-commit).
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25195/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25195?src=pr&el=tree)

```diff
@@            Coverage Diff            @@
##             master   #25195   +/-   ##
=========================================
  Coverage          ?   92.16%           
=========================================
  Files             ?      166           
  Lines             ?    52314           
  Branches          ?        0           
=========================================
  Hits              ?    48214           
  Misses            ?     4100           
  Partials          ?        0
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.62% <100%> (?)` | |
| #single | `42.25% <9.52%> (?)` | |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25195?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/packers.py](https://codecov.io/gh/pandas-dev/pandas/pull/25195/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL3BhY2tlcnMucHk=) | `88.85% <100%> (ø)` | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25195?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/25195?src=pr&el=footer). Last update [2448e52...b1347ae](https://codecov.io/gh/pandas-dev/pandas/pull/25195?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 an you merge master and update good idea, but closing as stale