Update ofxOculusRift.h

adding way to lock your view.  helpful if you're viewing video footage.  think of this as a constant lookAt.
Update ofxOculusRift.cpp

camera lock + disabled system destroy as it causes a crash.
Update testApp.cpp

added key command to perform view lock in the demo.
Update ofxOculusRift.cpp
Merge pull request #1 from jasonrwalters/master

view lock