Camera2: Improve shutter button

-Fix shutter button location
-Use smaller drawables

Before - http://goo.gl/4iCocE
After  - http://goo.gl/i63k8C

Change-Id: Id51fba53372bc7f67750e82063bfa7e1479ea503
Merge "Camera2: Improve shutter button" into cm-11.0
Merge branch 'cm' into HEAD