MB-10282: Remove TapConn class

We don't need this class since it doesn't provide anything more
than its parent class Connection contains.

Change-Id: Ieb101907bc7452b17d7989c10cb1ee72b208282b
Reviewed-on: http://review.couchbase.org/33912
Tested-by: Michael Wiederhold <mike@couchbase.com>
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>