Adds TwitterTweeter cog.
Adds the newline at end of files twitter_tweeter.{json,rb}.
TwitterTweeter: Removes extra rescue typo.
TwitterTweeter: Don't catch StandardError.
TwitterTweeter: Moves username option into JSON config file.
start.rb: Explicitly require --twitter-config to enable TwitterTweeter.
Merge pull request #42 from chfoo/issues/29-twitter

Adds TwitterTweeter cog.