GRN2-xx: Switch the relation between users and roles to make queries cleaner and faster (#1299)

* First steps

* Fixes in account creation flow

* Fixed most testcases

* more test fixes

* Fixed more test cases

* Passing tests and rubocop

* Added rake task to remove rooms

lib/tasks/user.rake

@@ -38,9 +38,9 @@ namespace :user do
 
       if u[:role] == "super_admin"
         user.remove_role(:user)
-        user.add_role(:super_admin)
+        user.set_role(:super_admin)
       elsif u[:role] == "admin"
-        user.add_role(:admin)
+        user.set_role(:admin)
       end
 
       puts "Account succesfully created."