Fix logs in how it should use exceptions.

While debugging issue with openstack CI, I identified a number of places where
exception was not doing the logging properly. Thus, this change set.

Ref link on logging:
https://wiki.opendaylight.org/view/Logging_Best_Practices

Patch 2: minimize the changes, but yet follow the Logging_Best_Practices.
Patch 3: missed change in same file, to keep changes consistent on patch 2.

Change-Id: Ie3dae66f24467ee2dd1113e9c0dd6a5d6ab0df5a
Signed-off-by: Flavio Fernandes <ffernand@redhat.com>