Android native call

This requires the following PR to openwebrtc: android-log-filter device-listing-fixes jni-fixes sdp-candidate, and and a server that uses the patch in this PR

sdp.js is currently linked from openwebrtc, which is assumed to have the same parent directory as openwebrtc-examples.

I've found the following issues so far:
- reregistering a surface doesn't work, but when registering the old surface, things will work again
- when the video source is switched, SRTP encoding fails
- remote view sent from Android falls behind and then catches up every now and then.
- no simple way to get rid of black borders on the video, will look into this as well
- when Firefox initiates the call it doesn't receive any remote video (probably sdpfail by me, will look into it)

Other than that this works for both incoming and outgoing calls to both Firefox, Chrome and OpenWebRTC