arrays/period: allow parsing of PeriodDtype columns from read_csv
Fixes: https://github.com/pandas-dev/pandas/issues/26934

Signed-off-by: Antonio Gutierrez <chibby0ne@gmail.com>

- [x] closes #xxxx
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

Hello @chibby0ne! Thanks for updating this PR. We checked the lines you've touched for [PEP 8](https://www.python.org/dev/peps/pep-0008) issues, and found:





There are currently no PEP 8 issues detected in this Pull Request. Cheers! :beers: 

##### Comment last updated at 2019-07-17 01:10:07 UTC > tests

Done! Thank you for the swift reply ;)! Can someone explain how the codecov/project failed? It looks as if the coverage in all the files dropped, even though I only changed 2 files.  > Can someone explain how the codecov/project failed? 

Happens sometimes, seems random.  Rebase and push again and it usually fixes itself > > Can someone explain how the codecov/project failed?
> 
> Happens sometimes, seems random. Rebase and push again and it usually fixes itself

Weird. Thanks for the suggestion though ;) thanks @chibby0ne  > thanks @chibby0ne

Thank you for your support @jreback @TomAugspurger @jbrockmendel @WillAyd !