Add ControllerSpecificationGenerator

Add ControllerSpecificationGenerator to the container and console command.
The spec generated by describe:controller were extending ObjectBehaviour.
This meant that the end user needed to add boilerplate code to each spec
to inject stub Request and Response. This is now done in the ControllerBehviour
class that all Controller specs will now extend.
Modify generator string identifier
Remove duplicate use reference
Add file exists test to prevent warning

Add a test for the file existing ahead of the include_one. Without
the tests the warning thrown would prevent the user from being prompted
to create the file and the spec functionality is blocked.
Merge pull request #43 from MageTest/feature/controller-spec-generator

Add ControllerSpecificationGenerator