Update template to work for Play 2.1.0 and some housekeeping

I've quickly updated the g8 template to work with play 2.1.0 and tidied up a few things:

* changed the Build.scala and sbt version to suit 2.1.0
* corrected a couple of types so that links work
* replaced literal versions with version from g8
* updated jquery to 1.9.1
* changed the background colour to match www.playframework.org