add hangouts! handler

@mdimas @vijaykramesh @erikogan @mrubens @orfah 

How does this look for a first-pass at a simple lita handler to create a new google hangout link on-demand?

I have it running in staging mode in the "Lita" chat room right now.

I made it so you have to write "hangouts!" (with the exclamation point) to create a new google hangout and each new room is simply created with a UTC timestamp.
Yeah, I was up in the air about this.

I made the string only match and activate the handler if the user starts with the word hangouts, but added the exclamation so that people wouldn't accidentally activate it if they were writing something like "hangouts isn't working" or something else.