#124 Add test helpers for unit and integration testing of securesocial controllers

I created a securesocial testkit project which is to be included with scope test by projects using securesocial. 
The testkit enables the testing code I described in #124 and its use is demonstrated in the scala sample.

Test helper classes and objects are in test-kit/src/main/scala/securesocial/testkit
Example specifications are in 
samples/scala/demo/test/ApplicationSpec.scala
samples/scala/demo/test/ApplicationScenario.scala

The first one demonstrates unit testing a securedAction, the second one is an integration test against the same action.

I have followed the same versioning convention as was used by the core project.

cheers
jean