Adds Shadow class for Android Support Library r18's DrawerLayout.

* Adds ShadowDrawerLayout including ability to mock opening & closing of DrawerLayout.
* Adds DrawerLayout unit tests.
* Changes dependency for Android compatibility lib from r7 to Android Support Lib r18.
Adds test for closing drawer of DrawerLayout and removes a few TODO messages.
Fixes broken close drawer test for DrawerLayout as well as various code style issues.