Add Spring to Play test application

This currently fails to build because of the line:

module.spring=${play.path}/modules/spring

in application.conf which gives:

    com.typesafe.config.ConfigException$UnresolvedSubstitution:
      conf/application.conf: 71: Could not resolve substitution to
      a value: ${play.path}

If the line is commented out, the application builds ok but fails at
runtime with:

    java.lang.NoClassDefFoundError: play/inject/BeanSource

[#52863047]
Add Spring Play module

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]
Merge 52863047-spring-play to master

[Completes #52863047]