Initial commit for resource files: drawable selector, fragment layout, and colors

Created a Drawable resource for the list item selector in the ListView of DrawerLayout.  Created a Layout resource for a Fragment.  Created a colors resource file with FlatUI colors.
Improved NavDrawerActivity

Implemented a method to switch fragments in the main view when list items are selected from the DrawerLayout.  Modified layout for NavDrawerActivity.
Created a Fragment for swapping views and modified the layout for the list item.

Expanded the layout for the DrawerLayout > ListView > list item.  Initial commit for ContentFragment.  Changed minSdkVersion in the manifest.