Fix a typo in log exception in the metering agent

This patch fixes a typo when there is a exception
when the agent try to invoke a method of the driver.
This patch also improves exceptions handling of
driver method calls.

Change-Id: I4fcf19fa84f178348abfb3563bbfd52f0dfcc095
Closes-bug: #1256041
(cherry picked from commit 272912b6d82af00a6f7bafc26d8ce7a79b09ef26)
Merge "Fix a typo in log exception in the metering agent" into stable/havana