PLT: Color attributes of medianprops etc are lost in df.boxplot and df.plot.boxplot
- [x] closes #30346 
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

Found out that not only `medianprops` info is lost, so is `whiskerprops`, `capprops` and `boxprops`, so I also added them alongside. Since this is a visualization PR, so add a screenshot to show what it looks like after the change

<img width="587" alt="Screen Shot 2020-01-24 at 4 16 26 PM" src="https://user-images.githubusercontent.com/9269816/73079678-eb468180-3ec4-11ea-9628-5ab13e73f15c.png">

gentle ping @TomAugspurger @jreback for feedback Thanks @charlesdong1991  This also closes #33868.
(see SO answer https://stackoverflow.com/a/62718470/3944322)