Fixed adapter-mock tests

* The `RTCSessionDescription` method used by the test for the mocked
adapter is now re-wired to the correct one from the adapter
Added new API proposal

* This should replace `application.js` soon
* Ignore API in build process until finished
* Added tests (WIP)
Added Node.js specific adapter code

* do not parse `adapter.js` in browserify as we need
`RTCPeerConnection` + friends globally
* re-added node.js specific adapter code