`test-bots` would not run in Vagrant, displaying
the error "ValueError: no such test method in <class
'bots_test_lib.BotTestCase'>: runTest" This was due to
the `BotTestCase` class inheriting from the TestCase
class, even though it was not a unit test on its own.
This commit removes the inheritance of TestCase and
specifies `test_define` as the `runTest` method in
`TestDefineBot`.
This test uses unittest and mock library. It mocks
'BotHandlerApi' class. This test works independent of
the rest of the code outside contrib_bots folder.
Merged with a few changes by tabbott to fix lint issues; we'll need to
do further work on this framework, but since it's not hooked up to
anything, it's reasonable to merge early so others can collaborate on
improving it.
