Captures user camera PubSub

Re: issue #84

- Setup of camera container and still image views
- Changed to front facing camera by default
- Added firebase channel for user images, and pushing encoded image data to those channels
- Tied in pubsub when viewing user cells in VBUserTableViewCell

Notes:
- I had to add autolayout for the navigation bar so that I could see it on my 3.5inch phone, but it messes with animations so those will look glitchy.
- Also, when opening the inputsource view, I'm replacing the user icon with an image if there is one from firebase, you'll see it update live. This is just to show it's working -- we can put a much better user image/design if we like the effect (it's quite cool to see it updating, and my plan is to eventually also suscribe to anyone's camera channel as well).