Added controller overlay (Filler Images for now)

demos/optical_bench/src/controller_overlay.cpp

demos/optical_bench/src/controller_overlay.hpp

demos/optical_bench/src/hmd_navigation_behavior.cpp

demos/optical_bench/src/hmd_navigation_behavior.hpp

...es/models/opticalBench/controller_overlay/Button_Menu.png

...s/models/opticalBench/controller_overlay/Button_Power.png

...ls/opticalBench/controller_overlay/Controller_Buttons.mtl

...ls/opticalBench/controller_overlay/Controller_Buttons.obj

resources/models/opticalBench/controller_overlay/Grip.png

...urces/models/opticalBench/controller_overlay/Trackpad.png

resources/models/opticalBench/controller_overlay/Trigger.png

...els/opticalBench/controller_overlay/menu_images/Grip1.png

...els/opticalBench/controller_overlay/menu_images/Grip2.png

...els/opticalBench/controller_overlay/menu_images/Grip3.png

...ticalBench/controller_overlay/menu_images/Grip_Select.png

...lBench/controller_overlay/menu_images/Trackpad_Rotate.png

...icalBench/controller_overlay/menu_images/Trigger_Grab.png

...lBench/controller_overlay/menu_images/Trigger_Grabbed.png

...ces/models/opticalBench/controller_overlay/untitled.blend

...es/models/opticalBench/controller_overlay/untitled.blend1