Go away from deployment specific charm names

Somewhat related to #34.

Many of the names of charm services listed in https://github.com/huntdatacenter/jujuna/blob/master/jujuna/settings.py are specific to our deployment which will probably break for other deployments/bundles.

Could quick ideas:

• Use/track actual charm names from the charm store and not the deployed service names
• Split up SERVICES list somehow so we can have one track only upstream charms from https://jujucharms.com/u/openstack-charmers/ and another for any other supplemental charms such as ntp, nrpe and etc?