TST: Add hex color strings test

[hironow]

It's already resolved. I added hex string color test.

closes #10299

[sinhrks]

Thanks! This looks to be fixed by #9894.

@TomAugspurger Please merge if it looks OK.

df = pd.DataFrame(np.random.randn(5, 5))
custom_colors = ['#FF0000', '#0000FF', '#FFFF00', '#000000', '#FFFFFF']
df.plot(color=custom_colors)

[jreback]

@hironow pls add a whats new note (bug fxies)

[hironow]

Sorry, unexpectedly closed.
I tried to 'git rebase' (and replace this PR's repo) to resolve conflicts, but I deleted this by mistake.
So, what should I do about this PR?

[TomAugspurger]

Does Github show a button for you to restore the branch?

[hironow]

@TomAugspurger Thanks for your comment. I restore this branch.
I've created a branch of duplicate name in my own forked repo.

[sinhrks]

Thanks for updates. Can you squash to the single commit? You can do it by:

1. Open your local pandas repository
2. git checkout master to switch to master
3. git remote add upstream https://github.com/pydata/pandas.git to register original url
4. git pull upsream master to update your master
5. git checkout pyconjp-2015-sprint
6. git rebase -i master to apply the master's update to PR branch

Pls feel free to ask me if you have any question.

[hironow]

@sinhrks Thanks for your comment and list of git commands.
I probably was able to squash this branch.

[sinhrks]

@hironow Thanks!