Upgraded to Scala 2.11

This commit upgrades to Scala 2.11. Changes include:

- Change imports of scala.reflect.BeanProperty into
  scala.beans.BeanProperty, as it is deprecated in Scala 2.10 and was
  removed in Scala 2.11
- Unify scala imports of @BeanProperty
- Upgrade only minimum amount of libraries in order to make it compiled in Scala 2.11
- Updated Gradle to 2.1