JCBC-271: Don't force reconnect on add.

This changeset prevents nodes from being added prematurely, leading
to duplicate channel assignments and exceptions. This also alignes
the CouchbaseMemcachedConnection functionality with the one
provided by CouchbaseConnection.

Change-Id: I7ca1ba2a91f8324259af48688a4daf4ae4283341
Reviewed-on: http://review.couchbase.org/25171
Tested-by: Matt Ingenthron <matt@couchbase.com>
Reviewed-by: Matt Ingenthron <matt@couchbase.com>