Add client to talk to RackConnect api

This patch adds a client to talk with the rackconnect api.
Currently, it only deals with adding/removing dedicated
loadbalancers and assigning/removing public IP's to
cloudservers. These are the only services which are 
currently (at the time of this PR) exposed via the 
rackconnect api: http://docs.rcv3.apiary.io/
This is a bit confusingly named. Should it be "get_for_server"? Also, can I pass a Server object here? I probably can, so you'd want to use utils.get_id(server).