DEV: update rubocop to version 0.77

We like to stay as close as possible to latest with rubocop cause the cops
get better.

This update required some code changes, specifically the default is to avoid
explicit returns where implicit is done

Also this renames a few rules

db/migrate/20141216112341_resolve_duplicate_group_names.rb

@@ -10,7 +10,7 @@ class ResolveDuplicateGroupNames < ActiveRecord::Migration[4.2]
                                 GROUP BY lower(name)
                                 HAVING count(*) > 1);'
 
-    groups  = Group.where id: results
+    groups = Group.where id: results
     groups.group_by { |g| g.name.downcase }.each do |key, value|
       value.each_with_index do |dup, index|
         dup.update! name: "#{dup.name[0..18]}_#{index + 1}" if index > 0