App Cleanup + Working Nav

Closes #58

- Navigation controller now inherits from UINavigationController
- Loads welcome controller implicitly
- New folders and grouping
- VBHUD and VBColor moves to utils
- UIViewController controller method category
- VBViewController for easy navbar access
- Corrects color definitions
- Fixes welcome screen scaling
- Adds VBNibView for easy custom views with nibs
- Removes controller transitions (for now)
- Changes view backgrounds to be transparent
- Removes redundant VBInputSourceControllerChangedSourceUserNotification
- Adds VBBarButtonItem for easy nav item creation
- Adds authorize trigger in the checkin controller