HTTP API fixes

Fixes API issues identified in these tickets:

https://www.pivotaltracker.com/story/show/60887336
https://www.pivotaltracker.com/story/show/60887246
https://www.pivotaltracker.com/story/show/60886000
https://www.pivotaltracker.com/story/show/60884508
https://www.pivotaltracker.com/story/show/60875916
https://www.pivotaltracker.com/story/show/60877478