Only display Cardboard menu when supporting HMDs.
Only display Cardboard menu when supporting HMDs.

Checks with FPLBase if Head Mounted Displays are supported before
offering the Cardboard menu item from the main menu.

Tested on Linux and Nexus 5.

Change-Id: Ic089a411ad390229bfe8f5d16e3bb77779860538

google/zooshi,google/zooshi,google/zooshi,google/zooshi,google/zooshi