Log exceptions from deploy and tear_down

If deploy or tear_down raise an exception, an error is set on the Node
and visible in the API, but nothing is logged. This change adds
logging in the ConductorManager of exceptions raised from either
method.

Change-Id: I17a9328770b6fc9fce167a189d9692b5c4c2687f
Merge "Log exceptions from deploy and tear_down"