Add __init__.py for unittest discovery
Change function signature for on_command

It doesn't seem like good practice to replace the values in sys, plus it
means print debugging becomes much harder.
Add tests for ach plugin
Add tests to autojoin plugin
Add tests to complete plugin
Add tests to crypto plugin
Support only the start of encode,decode in crypto plugin
Add tests for decide plugin
Add tests for define plugin
Add tests for echo plugin
Add tests for github plugin
Add tests for google plugin
Add tests for hash plugin
Add tests for help plugin
Add tests for heroku plugin
Add tests to http plugin
Add tests to humble plugin
Add tests to isup plugin
Add tests to joke plugin
Add tests to new plugin