hostgroup: Remove redundant and star imports

Also fixes some PEP8 errors.

Part of: https://fedorahosted.org/freeipa/ticket/3979
idviews: Add ipa idview-apply and idview-unapply commands

Part of: https://fedorahosted.org/freeipa/ticket/3979
idviews: Extend idview-show command to display assigned idoverrides and hosts

Part of: https://fedorahosted.org/freeipa/ticket/3979