BUG: Fixed Categorical.Equals with unordered
The original issue was already fixed. I added tests to verify (but no whatsnew entry).

This addes tests and a fix for https://github.com/pandas-dev/pandas/issues/16603#issuecomment-349290078 about `Categorical.equals`

Closes https://github.com/pandas-dev/pandas/issues/16603
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18822?src=pr&el=h1) Report
> Merging [#18822](https://codecov.io/gh/pandas-dev/pandas/pull/18822?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/04beec77e5a713dd90ba31dcf7ad43fd64ac55bb?src=pr&el=desc) will **decrease** coverage by `<.01%`.
> The diff coverage is `66.66%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/18822/graphs/tree.svg?width=650&height=150&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/18822?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #18822      +/-   ##
==========================================
- Coverage   91.56%   91.56%   -0.01%     
==========================================
  Files         150      150              
  Lines       48942    48947       +5     
==========================================
+ Hits        44816    44820       +4     
- Misses       4126     4127       +1
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.93% <66.66%> (-0.01%)` | :arrow_down: |
| #single | `41.74% <0%> (-0.01%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/18822?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/categorical.py](https://codecov.io/gh/pandas-dev/pandas/pull/18822/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvY2F0ZWdvcmljYWwucHk=) | `95.8% <66.66%> (-0.11%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18822?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/18822?src=pr&el=footer). Last update [04beec7...84b2640](https://codecov.io/gh/pandas-dev/pandas/pull/18822?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 rebase and push again, fixed some hanging by Travis CI