add voter mechanism to decide on current item
adjust code to feedback
make forward compatible with knp menu 2.0
make voters optional as they are not always needed
tweaked bundle configuration for voters
Merge remote-tracking branch 'origin/master' into current-item-voters

Conflicts:
	DependencyInjection/SymfonyCmfMenuExtension.php
pluralization fix
moved request handling to core, make voters actually work with knp-compatible interface
Merge pull request #49 from symfony-cmf/current-item-voters

add voter mechanism to decide on current item