Add useful sbt plugins

I highly recommend you using these useful plugins.

 - sbt-scalariform
 - sbt-scoverage
 - sbt-depedency-graph
 - sbt-updates

Other updates:

 - Scala 2.11.2
 - sbt 0.13.6
 - Latest scalikejdbc-play-plugin, mysql jdbc driver
 - scalariform applied source code