Set default touch-action for certain gestures

Fix sample to use correct event listener API
Use source target for touch-action calculation

currentTarget may be too high up the tree
Only setAttribute on an element node

Fixes #31
Disable Chrome-only touchevent touch-action

Behavior deviates too significantly from PE touch-action for now
Filed Chrome bug http://crbug.com/399765 to track
rough draft of trackX / trackY events

lowercase event names

Add default touch-action no matter how many listeners have been added before