Spring-Scala_2.11

Scala 2.11 has been released half of year from now. And majority of projects now supports both versions of Scala 2.10 and 2.11.

Here is the list what this pull request covers:

* 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
* upgrade minimum amount of libraries in order to make it compiled with Scala 2.11
* upgrade Gradle to version 1.12, which has [breaking change](http://www.gradle.org/docs/1.12/release-notes#incremental-scala-compilation), which allows to compile with Scala 2.11 `compiler-interface` (it doesn't work for Gradle 1.11)
* all tests are passing

Here is the list what this pull request _does not_ cover:
* not all libraries upgraded to the latest versions
* there is lot of deprecation messages in tests codebase, as there is no `scalatest` version `1.x` for `scala 2.11`, so this library was upgraded to latest `2.x` version
* there is no support of cross-build for both `2.10` and `2.11`

If any of those are necessary, I can add it.

Any feedbacks are appreciated. Thanks in advance.