Add Orientation event and update basic-gestures demo. 

Update: 9/28/2103
Backed out shake.js changes. I will leave that to you. Any feedback welcome thanks!

Update shake to use acceleration and accelerationIncludingGravity if rotationRate is present. Also add new build of Event.js and Event.min.js.

Not sure if I made the file structure correct or if this is even need by the main line project, but I wanted to offer you my updates. I made these changes in support of my custom build of fabric.js.

Thanks!