Add the functionality to allow for users to become company administrators [MJ-366]
Remove clean method and add unique_together to Administrators [MJ-366]
Update error message in tests to reflect the use of unique_together [MJ-366]
Add unique_together migration [MJ-366]
Unregister all dashboard models but Company [MJ-366]

Add a more intuitive select widget for admin selection
Moved everything from Staff to Employer group [MJ-366]
Remove mentions of Staff group from test docs [MJ-366]
Rename Administrators to CompanyUser; Rename admin on CompanyUser to user [MJ-366]
Remove auto addition/removal from Employer group [MJ-366]
Merge pull request #230 from DirectEmployers/user-company-mapping__MJ-366

Add the functionality to allow for users to become company administrators [MJ-366]