Fix action_result check

* change common.wsgi serialize_response to check for
  instances of Fault rather than webob.Response

Fixes: bug #1245546

Change-Id: I5a50234a8bd5d84918b87269054d23489e78629f
Added logging in taskmanager models && _() strings

Gone through taskmanager models, addding a few debugging statements to
some methods; should help operations teams find various instance task
timings.   Also made sure *every* logging statment used the _() method
and that it's consistent throughout the taskmanager model.

Change-Id: I07a58ecd1a7de0d6f998c7b263f86eb766973221
Merge "Added logging in taskmanager models && _() strings"
Merge "Fix action_result check"