Start pulling together summit demo elements
auto merge of #963 : larsbergstrom/servo/summit, r=jdm

We need to figure out what we need to implement/fix for the summit, and this page pulls together all of the elements we want to show.
deactive profiler when not in use; use newtype structs for task chans
workaround for broken cross-crate generic newtype structs

add issue number for newtype struct issue
cleaned up code in constellation to make it more maintainable
fix constellation being inundated with messages from script...