Instructions for using Android Studio.

You may want to see if you can reproduce this.

Notes:
1. We might want to distribute project files instead of using "Import" to create new projects.
2. We're using the "old" build system in Android Studio, switching to Gradle is a low-priority todo.
3. The name of the project/module should be "openglass" instead of "android" -- distributing our own project files would allow us to do this without complicating the instructions or having nested "openglass" folders.