Demo Project Update

I've updated the demo project to make it a little cleaner and easier to understand. Here's what this pull request changes:

 - Changed code to support storyboard initialization  
   - Move away from XIBs
 - Clean-up some project settings, images (moved everything to XCAssets), and code  
 - Updated Readme by adding more information, descriptive, text, etc.

This is just a little update. You may like it... or not. Great project by the way - I will be using it in the next update of my app: Runr (http://AppStore.com/Runr). Let me know what you think.