plugins/ban.py: Update to handle new cases

Updates ban.py handling some more cases

tests/ban_test.py: Add new mocks

Adds new mocks to get 100% test coverage for ban.py

setup.cfg: Remove ban.py from omit

Removes ban.py from the omit section

Reviewers Checklist

[ ] Appropriate logging is done.
[ ] Appropriate error responses.
[ ] Handle every possible exception.
[ ] Make sure there is a docstring in the command functions. Hint: Lookout for botcmd and re_botcmd decorators.
[ ] See that 100% coverage is there.
[ ] See to it that mocking is not done where it is not necessary.

coala / corobo