Modularized the ASCII response decoder and SASL states in
preparation for supporting multiple connections to different
servers in a single "Connection" object.

All the response states for GET and SET have been condensed into
one state that solely checks for the # of CLRFs. It trades off
value length checking for modularity.
Rewhacked the Connection.cc abstraction to support more than one internal
socket connection (bufferevent) for membase/pisces.

In this world, a single membase/pisces Connection is equivalent to having 1
connection to every server node in the cluster.