fixes #5246 - remove second host/class lookup impl so config groups are included in ENC output

(cherry picked from commit 46b3d8f1f5dff70b961266232f0041beabea8e0d)

fixes #4204 - add config groups feature - assign multiple config groups to a host or hostgroup

fixes #5053 - minor bug fixes to realm integration

fixes #4381: dns records are being update after changes to host when dhcp is also present

Fixes #4976 - ensure the process is really running inside a rake task

fixes #1809 - foreman realm integration

fixes #1966 - improved UI errors for proxy

fixes #3214 - set taxonomy for hosts created via Puppet from facts or a default setting

Fixes #4680 - Don't append periods to unqualified unmanaged hosts

fixes #4256 - makes columns sortable in the UI