DOC: Exposed arguments in plot.kde
The documentation for `plot.kde` did not show the `bw_method` and `ind` arguments, which are specific to `plot.kde` (and `plot.density`, which refers to the same method).

There is also a change in the actual code, and a corresponding test added. I added an option for `ind` to be an integer number of sample points, instead of necessarily a `np.array`. I image that a user typically just wants a number of equidistant sample points, and does not want to construct an array.

- [X] tests added / passed
- [X] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

Comments very welcome.

Hello @tommyod! Thanks for updating the PR.





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

##### Comment last updated on February 01, 2018 at 14:12 Hours UTC Ran the `flake8` tool while in the wrong subdirectory locally. Will fix the errors tomorrow and push. # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19229?src=pr&el=h1) Report
> Merging [#19229](https://codecov.io/gh/pandas-dev/pandas/pull/19229?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/35812eaaecebeeee0ddf07dee4b583c4eea07785?src=pr&el=desc) will **decrease** coverage by `<.01%`.
> The diff coverage is `42.85%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/19229/graphs/tree.svg?height=150&width=650&token=eZ4WkYLtcO&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/19229?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #19229      +/-   ##
==========================================
- Coverage   91.67%   91.67%   -0.01%     
==========================================
  Files         148      148              
  Lines       48553    48556       +3     
==========================================
  Hits        44513    44513              
- Misses       4040     4043       +3
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.03% <42.85%> (-0.01%)` | :arrow_down: |
| #single | `41.71% <28.57%> (-0.01%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/19229?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/plotting/\_core.py](https://codecov.io/gh/pandas-dev/pandas/pull/19229/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb3JlLnB5) | `82.23% <42.85%> (-0.18%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19229?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/19229?src=pr&el=footer). Last update [35812ea...826a124](https://codecov.io/gh/pandas-dev/pandas/pull/19229?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 @jreback, @TomAugspurger  - I have addressed the comments.

- Wrote an additional test.
- Fixed linting errors.
- Type checked with `is_integer`.
- Added `whatsnew` comment. @jreback Friendly reminder to consider this PR, in case it has been forgotten. If there is anything else that needs to be done, please let me know. @jreback I believe this PR is good to go now. Thanks @tommyod!