Update post callback to set collection and content id of the posted content item
Fix bug with writer. Post callback should have signature, (err, response)

Conflicts:
	tests/spec-list.js
Writer passes err along to callback after ryan's change
Make sure that stateToContent puts .collection on reply content, not just top level
CollectionUpdater passes opts.collection to its statetocontents
Merge pull request #194 from Livefyre/posting-to-collections

Small changes mostly around Writing to Collection Streams