Add traceback error
Add traceback error

This patch adds the traceback error to be emmitted to the stderr when
Kuryr catches the exceptions for making debugging easier.

Change-Id: I74c6dc8c075c06f3fe3b9508e2dc5f523196b795
Signed-off-by: Taku Fukushima <d385cb54d860d8a5dcc6157b54cf213091772451@gmail.com>

celebdor/kuryr,midonet/kuryr,celebdor/kuryr-libnetwork,openstack/kuryr,celebdor/kuryr,midonet/kuryr,celebdor/kuryr-libnetwork,celebdor/kuryr-libnetwork,midonet/kuryr,openstack/kuryr