Split out LoginView, introduce ReactiveCocoa

LoginView is self contained and responsible for drawing and laying out
the view.  The LoginViewController monitors for events (via ReactiveCocoa)
and fires off API calls as needed.
Add a few UI niceties. 

* Remove filler for a more accurate development experience.
* Colorize registration button.
* Adjust username and password text field behavior appropriately.
TestFlight integration.
Media upload implemented in HTTPClient.
Load CaptureViewController immediately.
Camera view and device controller.

This is largely a reorganized version of the AVCam demo project from
Apple.
A bit more info in the README
Rename CaptureViewController
Store captured image on CameraController

To be monitored via RACObserve() for upload.
Whitespace.
Use CameraView instead of UIImagePickerController.
Overlay LoginView in CameraViewController

This removes any need for a LoginViewController.
Give the client knowledge of authentication state.
Update HTTPClient and root resource post-authentication.