Use id instead of multiaddr for indentification

[mkg20001]

Peers would be identified by their id on the servers and locally the clients would "build" the multiaddr of the peers using this.ma.decapsulate("ipfs").encapsulate("ipfs/" + peerId)
This would remove the following features:

• Using websocket-star without cryptoChallenge (which is insecure or at least gives other people to "claim" the address)

This would solve the following problems:

• A peer that listens on the signaling server /dns/domain.tld/ws/p2p-websocket-star (http://domain.tld) would be unable to dial peers listening on /dns/domain.tld/wss/p2p-websocket-star (https://domain.tld)
• Complicated if-code
• Some untested edge-cases such as dialing to a server with cryptoChallenge off when id is set.

[mkg20001]

@diasdavid Thoughts?