Remove unused hooks

Remove unused until there are either ansible tasks tagged for them, or explicit hooks in hooks.py registered.

Any hooks added to the default_hooks of the AnsibleHooks helper will result in ansible trying to run all tasks tagged with the hook name when the hook is triggered (ie. config-changed), but ansible-playbooks errors if it doesn't find any tasks with the tag.

Example of deploying this charm stub: http://paste.ubuntu.com/6442336/