Don't commit when preparing the release

This allow us to inspect the changes before committing them.

Author: rafaelfranca

tasks/release.rb

@@ -294,9 +294,9 @@
     sh "git push --tags"
   end
 
-  task prep_release: %w(ensure_clean_state build bundle commit)
+  task prep_release: %w(ensure_clean_state build bundle)
 
-  task release: %w(prep_release tag push)
+  task release: %w(prep_release commit tag push)
 end
 
 module Announcement