Create Dashboard Activity layout

Dashboard Activity Layout following our current wireframes https://www.flinto.com/p/a0de3ed3

/cc @fcduarte @amitbharadwaj 
I'm just lazy and used the pattern shown [here](https://github.com/thecodepath/tumblrsnap/blob/master/src/com/codepath/apps/tumblrsnap/activities/MainActivity.java#L76)