Add a new "Quality Profile Administrator" role

Having this role should be required to edit a quality profile.

Required changes:

• Create a new role "Quality Profile Administrator" and make it mandatory to perform any action on the quality profiles
• Rename "System Administrators" page into "Administrators"
• On this page, add a new "Quality Profile Administrators" section like the "System Administrators" one
• On a fresh install, the "sonar-administrators" group should be belong to this new role
• On a migration, every user and group belonging to "Administrators" should be added to this new role