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.
Add one function (get_bot_botname_response()) that generates response
from the given input and replies back to the handle_message with the final
content of response to be sent. Also add code to bots(except followup) to
reply to private messages along with stream messages.
