Import nova's looping call.

The looping call implementation had drifted in nova away from what
was in oslo. Update olso. I will move nova over to this code in a
later review.

Change-Id: I0e9214a150223dcd4fb1d695db36961bba794166
Finds dependencies of configured modules for update.py

Looks up import lines in the configures modules and finds dependencies.
Did not load modules since it seemed as an overkill

Fixes bug #963509

Change-Id: I690cdf6fb149bbe243add3a35b96f6045ebe10f4
Merge "Import nova's looping call."
Merge "Finds dependencies of configured modules for update.py"