Adds the new contracted launcher behaviour
Also fixes a few bugs
cogl vapi file updated to fix a vapi bug
had to modify mail.c to make the launcher's grabbale size to be one pixel bigger
modified:
targets/mutter/main.c
tests/unit/test-launcher.vala
unity-private/launcher/launcher-child.vala
unity-private/launcher/scroller-model.vala
unity-private/launcher/scroller-view.vala
unity-private/launcher/scrollerchild-controller.vala
unity-private/launcher/scrollerchild.vala