Received messages do not generate good contact info

[schancel]

Currently, when receiving a message from an unknown party, the client adds a contact for the address and a "Loading..." name with no public key or relay information.

However, the address and the source pubkey are in the messages for the purpose of being able to quickly verify the integrity of the message and decrypt it!

The client should add the address as the username, and the pubkey to the contacts list. Attempted messages sent to the party before the keyserver metadata can be loaded should be disallowed. Optionally, we can provide a "reply-to" and some name in the message as well.