Add Spring to Play test application

The Spring Play module was built from:

https://github.com/wsargent/play-2.0-spring-module

as per the README using sbt 0.12.3. The resultant
JAR was stored in the application's lib directory.

The controller was refactored to use a Spring Bean of the Probe
class which is explicitly obtained via the Spring Play module API.

[#52863047]