Enable all new cops

.rubocop.yml

@@ -1,3 +1,5 @@
+AllCops:
+  NewCops: enable
 Metrics/BlockLength:
   Exclude:
     - test/**/*_test.rb # We define specs in blocks, which by nature get large.

config.ru

@@ -2,6 +2,6 @@
 
 $LOAD_PATH << '.'
 
-require 'lib/contact.rb'
+require 'lib/contact'
 
 run Sinatra::Application

lib/contact.rb

@@ -81,7 +81,7 @@ module Contact
   end
 end
 
-require_relative '../config/environment.rb'
+require_relative '../config/environment'
 
 Pony.options = {
   to: Contact.config.mail_to,