Release version 0.7.0

Drop EventTarget support on Gadget.
Add declareAcquiredMethod, allowPublicAcquisition.
Prefix attribute non part of the API by __. Such method/property can be rename
in next versions without any compatibility support.
Use base element in iframe to get the same link behaviour with or without
iframe.

package.json

 {
   "name": "renderjs",
-  "version": "0.6.1",
+  "version": "0.7.0",
   "description": "RenderJs provides HTML5 gadgets",
   "main": "dist/renderjs-latest.js",
   "dependencies": {