Correctly check docstrings in pep8 tox environment
Correctly check docstrings in pep8 tox environment

PEP 257 requires that there be no blank lines between a class's
declaration and its docstring. The pep257 library includes a check for a
blank line (D203) but excludes it from the list of checks to run when
using `pep257.check`. flake8-docstrings 0.2.2 introduced a change that
stopped using this function and instead used the `PEP257Checker` class.
Unfortunately this class requires that all registered checks, include
D203, pass.

Until either pep257 or flake8-docstrings has been updated to address
this, the version of the latter shall remain pinned at the last release
to use `pep257.check`.

iheartradio/Henson-Database