Some major changes:
* the charm has been rebased (from a Python perspective) to be rooted in
the charm directory. This is a single root.
* Imports have been changed so that the don't add lots of imports to the
namespace of the module doing the import.
* The code that used to run at module import time has been made lazy
such that it only has to run if the relevant functions are called.
This includes restart_on_change parameters, the harden function and
the parameters to the guard_map. Appropriate changes will be
submitted to charm-helpers.
* Several tests had to be re-written as (incorrect) mocking meant that
text fixtures didn't actually match what the code was doing. Thus,
the tests were meaningless.
* This has had a net positive impact on the unit tests wrt to importing
modules and mocking.
Change-Id: Id07d9d1caaa9b29453a63c2e49ba831071e9457f
9c12812735