Soften up some of the UI elements on Android

A few tweaks to font sizes, weights, and colors to make the UI look less Gingerbread-ish. Also makes the touch targets for the items in the hamburger menu a little taller, so they are easier to touch.

These changes can be previewed here:

http://imgur.com/qwtBzlm
http://imgur.com/yZmH7ZQ

Those are images from the Android Studio UI editor, because I don't know how to build correctly for Android yet. The UI specific stuff builds fine though, so I doubt there will be a problem getting it to build.

Also, anything marked with the xmlns 'tools' won't show up at runtime, they are just placeholders for the UI editor.