Updated Documentation, New Methods, Improved Selection

New Methods / Functions:
The `[KioskDropboxPDFRootViewController fileName]` function has been added which provides an easy way to retrieve the name of the last downloaded file.

Updated Documentation:
Added a few steps to explain adding DropboxBrowser files and added a section describing Delegates, Functions, and Results.

Improved File / Folder Selection:
Previously, only the TableView accessory button could be used to download / open files. Now when tapping anywhere in the TableView cell the proper function is called and the item is deselected after selection.