A mass of UI changes. I would break the commit up, but it was a bit of a
messy update.
 - Most of the UI logic has been moved into AppDelegate, for example
   displaying the authentication screen.
 - Tidied up the UI for the log view a little.
 - Removed some UI segues and properties that were not needed.
 - Removed warnings that would come up due to pushing segues before the
   calling controller had displayed.
 - Removed gradient drawing errors.
 - Pin view now displays when minimizing the app from any view other
   than the main view.