add webserver smoketest

[kkuehlz]

#113 caused jinja to hard fail since the show_topic method didn't have a docstring. This is especially annoying because Marathon uses the webserver to healthcheck the bot—so a broken webserver leaves ircbot in a deploy loop. We can't reasonably expect people to remember to docstring methods when writing plugins. We should have make test run a smoke test that ensures the webserver 200s to catch these errors.