front: Added support for MOGA controller via MOGA Pivot app.

Before, users had to use the third-party MOGA Universal Driver app.
Great app, but requires root for full analog compatibility, and
still doesn't provide analog control for pre-Android 3.1 devices.
That left
 - unrooted users*
 - pre-3.1 users
without analog control.

This commit fixes that.  Now, if the user downloads the official first-
party MOGA Pivot app, they get fully-mappable analog support all the
way back to Android 2.3, no root required.  The only limitation is that
menu navigation via the controller is only supported for the MOGA Pro
in HID mode B.

* (Previously, unrooted users with Android 3.1+ and a MOGA Pro
  controller had full analog support if they switched controller to HID
  mode B.)