Make scrutinizer happier

I applied the patches in scrutinizer and unify the `@return self` around the project.
Just to make scrutinizer happier… addresses #366
It's a documentation problem in `TestCommonBundle:WebTestCase` then.
Maybe it is that `getServiceCallableName` doesn't sound a good name to me for the task it does, since it should return one or more services that should be checked for existence.

Names aside, I don't find the need to return anything than a `service[]` other than pure lazyness. :stuck_out_tongue_winking_eye: