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.
How about making the command `+hangouts` or `+hangout` instead of `hangouts!`?

That seems like something that people wouldn't accidentally type and it is pretty intuitive: you're creating a new hangouts.