Adding jshint task

I'd like to propose we use jshint on the project. I added a gulp task in this change and started doing some of the small modifications needed to please it. Client is in a OK state, no much work left. Server side is much worse, but mostly easy fixes like missing semicolons and unused variables. I know it can be very annoying at times, but I think it's worth it long term. We can adjust the configuration to our liking.

I volunteer to clean up the code, but want to make sure we have agreement first. I'll do client code first and leave server cleanup for after irc-server integration to reduce merge pain.

Ideally this would go into CI in the future, to make sure it's kept clean.