Merge pull request #304 from Livefyre/s_dellworld_rbi

Storage stores content according to keys which involve the collection.id
Update streamhub-share dep to v0.1.5
Merge pull request #306 from Livefyre/t_sharefix

Update streamhub-share dep to v0.1.5
Merge pull request #305 from Livefyre/rc

Rc -> master 2.15.3
Adding a check for stored content's 'updatedAt' field in state-to-content.