Update the Scalatra Templates for Scala 2.11 & Jetty 9.2.3

# Scalatra Templates for Scala 2.11 & Echo Service Example.

### Enable a quick way to create a Scalatra Project by using a Maven Profile `gen-scalatra` and a Echo Service YAML specification.

Call by:
`mvn -P gen-scalatra`

### The Scalatra template now uses Scala 2.11

* Moved to Scala 2.11.2
* Updated the dependencies to use latest Jetty as well as Akka
* Added the SBT Dependency Graph plugin
* Build Properties now use SBT 0.13.5
* Updated the sbt executable.