This was introduced in PR#930. The first commit had the route's
check if the flushOutbound() returned false, and if so would
locally unlock/lock the connection's lock. Unfortunately, this
was replaced in the second commit (a6aeed3a6b)
to the flushOutbound() function itself.
This causes the function closeConnection() to possibly unlock
the connection while calling flushOutbound(), which if the
connection is closed due to both a tls timeout for instance
and explicitly, it would result in the connection being scheduled
for a reconnect (if explicit gateway connection, possibly route).
Added defensive code in Gateway to register a unique outbound gateway.
Fixed a test that was now failing with newer Go version in which
they fixed url.Parse()
Signed-off-by: Ivan Kozlovic <ivan@synadia.com>