Refactor negotiation code to not require server struct

Now we use a bare connection object rather than a server structure.

Change-Id: I8d0b2218af1781bb2cdf6cc1132f211f2d90fdb3
Reviewed-on: http://review.couchbase.org/31425
Reviewed-by: Brett Lawson <brett19@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>