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
Add __init__.py for nova scheduler filters

To use these filters out of tree right now, you have to specify them in
nova's available_scheduler filters by full path. But in order for the
modules to be found and loaded, you must have an __init__.py.

Change-Id: I4816d9dbe0e93056792fad48e6228ffdd531e346
Cleanup mock patch without `with` part 2

A good idea because it makes the code easier to read to get rid of
the `with` using mock.patch and mock.patch.object in favor decorators,
where possible in the tests.

This patch affects Nova driver tests.

Change-Id: Ifd2e4d36c3cbcf82cb9b83c375ba0a3e98019adf
Merge "Log exceptions from deploy and tear_down"