Remove uneeded namespace includes

Change-Id: I8f2aa9fa8938ec4f75d8bfe055c46730b8f6a43b
Reviewed-on: http://review.couchbase.org/42580
Tested-by: Jeffry Morris <jeffrymorris@gmail.com>
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>