Vector Drawables

[daneren2005]

Convert use of multiple pngs to use vector Drawables instead. For now it will benefit from not needing to download and store separate versions of each Drawable. Current gradle version will automatically convert them to the appropriate sizes. The latest release of the support library added the ability to use the vector Drawables directly on older versions of android. If I switch now later when I can upgrade to the v23 support library I can dramatically lower the size of the apk.