Add juju support to lcm

This adds basic Juju support to the lcm.
- Add a ModelObserver to watch model changes and update nsr_lcm when a
  charm is deployed and either ready or blocked.
- Refactor DeployApplication to take ns and vnf record as parameters and
  extract necessary information to deploy and configure charm
- Add basic checks for proxy/non-proxy charm
- Rebase against latest lcm changes
- Automatically remove a charm when deleting the associated network
  service
- Revert lcm.cfg
- Address changes per discussion this morning

TODO:
- Finish adding non-proxy charm support (need to pick appropriate
  example to highlight this)

Signed-off-by: Adam Israel <adam.israel@canonical.com>
Change-Id: Iffd24293722a050630bcb5812d3f15217067b238