Set default branch for git review/gerrit.

Switch amulet tests to stable.

Switch to using stable charm-helpers branch.

Change-Id: I019337945f3417cc5b9cfc133c15cdab68b647e6

Using the new version of the sync tool which removes the charmhelpers
directory before syncing, run charm helpers sync to find any unexpected
missing dependencies.

Change-Id: I4f22eafc217f94992210592f4219ff6bf23eeef0

Change-Id: I02dd12ae127870747175237d9b7c998e0c2ac0cd

Juju 2.0 provides support for display of the version of
an application deployed by a charm in juju status.

Insert the os_application_version_set function into the
existing assess_status function - this gets called after
all hook executions, and periodically after that, so any
changes in package versions due to normal system updates
will also be reflected in the status output.

This review also includes a resync of charm-helpers to
pickup hookenv and contrib.openstack support for this
feature.

Change-Id: I4cf3c3389def2a0dc9d0cd286aa8190cbfa59f9a

Add charmhelpers.contrib.hardening and calls to install,
config-changed, upgrade-charm and update-status hooks. Also
add new config option to allow one or more hardening
modules to be applied at runtime.

Change-Id: I7752d72cc5a3f47fe66bca23aac730d76af8556a