Profile keypair separate to peer identity

[caolan]

A keypair that can be used by multiple peers (owned by the same person). Peers should register themselves with a DHT using the profile key so new peers can be found for a known profile.

[caolan]

Perhaps this could be solved via the petnames system? #39

1. I already have a public key for one of my collaborator's machines
2. They install the mutiny app on another machine and want to collaborate from there too, so they publish a special contact (marked rel=me) from their existing peer pointing to the new one.
3. My mutinyd updates it's contact list and notices another peer ID associated with my contact, adding it automatically, nested under the same petname (?)