README: Add project status

[aisouard]

State the project's status and implementation progress.

[t-mullen]

Hi @aisouard! Do you plan to continue development on this? Node.js is in desperate need of a low-dependency WebRTC stack and I think this project could fulfill that. (As I'm sure you're aware, the other node-webrtc has large binaries, and the original webrtc-native appears to be unmaintained)

If you're still interested in working on this, I'd be willing to help fill any gaps in your tests, as well as running some "in the field" trials with a few projects I maintain. I think that the simple-peer test cases would be a good place to start, since they are fairly comprehensive.

[aisouard]

Hello @rationalcoding,

Thanks for your interest, I plan to continue this project, but I'm not sure when.
The W3C specs are constantly changing (this issue comment for instance). Perhaps I just should provide backward compatibility for the "callback-based" implementation of WebRTC.

I'll do a planning when I'll get the time, I'll keep focusing on the lib's stability by adding more but lighter unit tests.