Added support for deleting directories
Merge branch 'dev' of github.com:EricLagerg/core into EricLagerg-dev
Only try to delete a path if it is a directory

Update @EricLagerg's fix for #180 to more carefully check the
``errno`` attribute of the caught ``OSError`` exception and
only try to use shutil.rmtree if the OSError was raised
because the file is a directory.

This helps prevent getting other instances where OSError would be
raised, for instance a file permission error, from getting eaten.

Addresses https://github.com/openelections/core/issues/180
Merge branch 'EricLagerg-dev' into dev