Create Duplicate Groupname Checker

[jacobdadams]

Add another org-wide checker to identify duplicate groupnames. Long-term solution to #45.

[steveoh]

Group names are not uniquely enforced in Hub or we are able to have "duplicates" because of how auditor looks for groups?

[jacobdadams]

Group names are not unique within an AGOL organization, and auditor looks for groups within the whole organization (groups = self.gis.groups.search('title:*')). I'll need to check to see if we can add an owner parameter to that search string; that may allow us to restrict it to groups owned by the UtahAGRC user.

It's similar to the duplicate item name check—internally, it appears to rely on the ItemID for uniqueness, and everything else is fair game.