Use vars file more consistently for version-specific configuration

[jturel]

We're inconsistent in how we handle performing actions along the lines of For X Satellite version(s) perform Y action. Currently, some data/configuration comes from the vars file for the given Satellite version. In other cases we have things like this in the playbook:

# due to support for remote databases in 6.4+ the postgres user (and server) may be missing                                                                                                   
- name: Install postgresql-server                                                                                                                                                             
  yum:                                                                                                                                                                                        
    name: "postgresql-server"                                                                                                                                                                 
    state: latest                                                                                                                                                                             
  when: satellite_version in ["6.5", "6.6", "6.7"]

This pattern means that each time there's a new Satellite version we need to review all of the tasks and make sure to update the satellite_version array as necessary which means we are going to miss things. The solution is to add additional configuration in the vars files. For the above example we could do something like below in roles/satellite-clone/vars/satellite-X.yml:

postgresql_package: 'postgresql-server'

Then the playbook can become:

- name: Install specified postgresql package
  yum: postgresql_package
  when: postgresql_package

When we release a new Sat version and add support here the best case scenario is that we copy the vars file from the previous version, make any necessary edits, and not have to worry about doing a full-fledged review of the playbooks themselves.

[evgeni]

this happened, mostly in #408

closing as done :)