[FrameworkBundle] new method to create shorthand name from full Controller name

Bug fix: no
Feature addition: yes
Backwards compatibility break: no
Symfony2 tests pass: yes
Fixes the following tickets: n/a
Todo: see if there's a more elegant way of finding the controller
License of the code: MIT
Documentation PR: n/a

The code now loops over all existing bundles and uses a regexp to see if it's the one we're looking for. Perhaps someone knows of a more efficient way to do this, but I wasn't able to find it.