Made AddressbookManager.transaction a class method

Ignore-this: 948b0e7ab6b72a9d3cb55bcc3d7377a2

darcs-hash:20130315200313-b22ec-37d5c48e6bd90fd9ae199cd52b33036c5e72fce6
Added presence subscriber for itself to Account

Ignore-this: f191a57db94c2685a26a323b1d126d6f

darcs-hash:20130319100800-56b4d-90c047700bc855a153c1dd981ab865961811dee3