OrbitControls minor fixes.

I recently tried to use the relatively new ability of OrbitControls to re-assign the mouse button inputs using `controls.mouseButtons`and noticed a small bug. 
The control still calls `update()` internally and also raises the start/change/end events even when the input  mouse/kb/touch event has not caused a state change.
This causes a few minor issues with changing cursors and also with the `autoRotate` speed

These fiddles demonstrate the problem and my fix;

issue: http://jsfiddle.net/satori99/1bmtu6k1/6/
fix: http://jsfiddle.net/satori99/ft8nvs2c/1/

This PR adds checks for `state !== STATE.NONE` before updating or raising events
I tried other examples that use OrbitControls and it does not affect existing code.