Removed deprecation notice from RajawaliActivity and added class level
comments directing developers to the various options for managing the
Rajawali engine.

Signed-off-by: Jared Woolston <jwoolston@tenkiv.com>
Merge pull request #550 from Tenkiv/deprecation_update

Removed deprecation notice from RajawaliActivity

Thank You!
BIG UPDATE. A necessary change to prevent confusion and future problems.
Rajawali's coordinate system has changed to conform to the OpenGL
standard. The z axis has now been inverted. Either invert your camera's
z coordinate or call mCamera.setLookAt(0, 0, 0); to restore your scene.
#558 #505
Updating.
Merge branch 'master' of git://github.com/MasDennis/Rajawali