added drawable resource

Imported mock-up of the graph that will go on our YouAndYourCommunity
activity.  This is located in the drawable-hdpi resource folder.
added graph mock-up and changed descriptive text

Added PovertyLineGraph.png to the YouAndYourCommuity xml file to serve a
a mock-up for the graph that will be generated by our algorithm. I also
edited the text describing the graph, but this may still need work.