Add unit tests for os-svc-daemon

Adds a set of unit tests for os-svc-daemon to verify the output
of running it with various options.  Includes a base test class
with some convenience functions for testing scripts.

Change-Id: Id54291686d39ab1b9f0ce4848a2fcf3c18a9ea18
Merge "Add unit tests for os-svc-daemon"