Derive token from cid, bring back the custom version of peerjs

Since [this commit](https://github.com/bitpay/copay/commit/c5aa3372d2174e7c2c1bfb40ee5e5e89ba88084c) we have been using a peerjs version without the ability to reconnect.

This PR adds back that version and derives the token from the CID to avoid other issues.

Closes #779