Enabling Touch Events

1st take on fixing #166

touch.js from http://mxr.mozilla.org/mozilla-esr17/source/b2g/chrome/content/touch.js?rev=df7835caf208

Testable on
 * http://paulirish.com/demo/multi
 * http://openlayers.org/dev/examples/multitouch.html
 * http://phoboslab.org/crap/mt.html
 * google "test multi touch"