Add and apply Style/RedundantArgument rubocop rule

This rule was added in rubocop 1.4.0.

.rubocop.yml

@@ -490,6 +490,9 @@ Style/Proc:
 Style/RaiseArgs:
   Enabled: true
 
+Style/RedundantArgument:
+  Enabled: true
+
 Style/RedundantCondition:
   Enabled: true
 

app/controllers/management/users_controller.rb

@@ -47,7 +47,7 @@ class Management::UsersController < Management::BaseController
     end
 
     def user_without_email
-      new_password = "aAbcdeEfghiJkmnpqrstuUvwxyz23456789$!".split("").sample(10).join("")
+      new_password = "aAbcdeEfghiJkmnpqrstuUvwxyz23456789$!".split("").sample(10).join
       @user.password = new_password
       @user.password_confirmation = new_password
 

app/views/admin/settings/_content_types_settings_form.html.erb

@@ -6,8 +6,8 @@
     <% Setting.mime_types[group].each do |content_type, mime_type_value| %>
       <span class="content-type">
         <%= check_box_tag content_type,
-            setting.value.split(" ").include?(mime_type_value),
-            setting.value.split(" ").include?(mime_type_value) %>
+            setting.value.split.include?(mime_type_value),
+            setting.value.split.include?(mime_type_value) %>
         <%= label_tag content_type, content_type.upcase %>
       </span>
     <% end %>