[Android] User configurable input overlay scaling

I extended this from simply shrinking the B button. I resized the B, X, Y and start buttons, but the main thing is user configurable scaling of the onscreen input. The minimum is 50%, the maximum is 200%, and the default is 100%.

Screenshots:
http://i.imgur.com/SBcxDsi.png
http://i.imgur.com/lv16N0Z.png
http://i.imgur.com/e2XFj08.png
http://i.imgur.com/1AJ4nQn.png
http://i.imgur.com/juhoXok.png
(This last one has a very slightly smaller B button to better match actual controller)
http://i.imgur.com/K63Zl4A.png
That would be awesome if you could do that. Then we can finally get this merged in.