Breakdown Presence requirements and features

Karissa made significant headway on presence, but it was left incomplete: !8

Three plus user stories this applies to:

• As a space member, when I navigate to my space #show page, I want to see a little green dot next to a space member's name/pubkey when they are online, so I know that they are online
• As a space member, when I navigate to my space #show page, I want to see a little red dot next to a space member's name/pubkey when they are offline, so I know that they are offline
• As a space member, when I navigate to my space #show page, I want to see a timestamp next to a space members name/pubkey displaying the 'last seen' time, so I know the last time the space member replicated with me

To finish this, we need to:

• make sure the peer-add event is firing.
• generate and send a signature as well as the publicKey
• verify the signature
• decide what to do with those that verification
• ensure the peer pubkeys are being stored properly in our connections leveldb
• write tests (might have to fake a hyperswarm instance)