Renamed FrameworkContext to TokenContext 

Renamed FrameworkContext to TokenContext including all related classes, documentation and tests.

Following a suggestion at symfony live 2014 in Berlin, this commit renames the FrameworkContext to TokenContext. I hope, that I found every related occurrence outside the usual code - so documentation, test classes, typehints are affected as well.

As a side note: All tests still pass, but I had to switch to the dev version of phake, because it threw serialisation errors in its current stable version (see https://github.com/mlively/Phake/issues/155). This was the case in the master branch as well, so it had nothing to do with the introduced name changes.