Description of problem:
Using foreman-rake console or erb code to list all members of a Config Group will always result in an empty host list.
Reason: when we add a host to a Config Group foreman adds the host to the host_config_groups table on postgres with host_type = 'Host::Base'. However, when looking up i.e. when doing myconfgroup.hosts it requires host_type = 'Host::Managed'.

Steps to Reproduce:
1. Create a Config Group
2. Add a Host to the Config Group
3. Optionally, add also a Host Group to the Config Group
4. foreman-rake console
5. ConfigGroup.where(:name => "name of your CG").hosts
6. ConfigGroup.where(:name => "name of your CG").hostgroups