Play 2.3 and Webjars

This moves to Play 2.3, which unfortunately means having to put  
```scala
import play.api.Play.current 
```
everywhere.  This is annoying enough that I'm considering move to dispatch for HTTP.

I've also moved to using webjars(http://www.webjars.org/) for javascript dependencies. Clearly, this is an insane idea, but actually it works rather nicely for what I want here and means I don't have to fiddle around with another build tool.