MB-4695 allow http://<server-name> when adding node to cluster

- implemented correct url parsing on server side

- removed host:port parsing from the client code

- unified the interface of addNode and doClusterJoin
by introducing hostname parameter for doClusterJoin
with preserving the old parameters for backward compatibility

Change-Id: I2aad5383bb003b116c01ab412f0eb43690e192c5
Reviewed-on: http://review.couchbase.org/27900
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>