New Methods, Framework Update, 4-inch Screen Support, Updated ReadMe

Now use the one line `displayDropboxIn` method to present the Dropbox Browser, instead of using 40+ lines of code. It is now easier to implement. Check the ReadMe for more details on the new method.

The Sample Project now uses Dropbox Framework 1.3.3

Dropbox Browser now fully supports 4-inch screens (iPhone 5, and iPod Touch 5). It also dynamically sizes content in the event of screen size changes / orientation changes.

The updated ReadMe shows a ChangeLog and the new convenience method.