Fix doble submit specs

We have a custom implementation to avoid doble submissions which causes
some custom problems 😌

This commit should fix the following three specs
spec/features/comments/legislation_annotations_spec.rb:367
spec/features/comments/legislation_questions_spec.rb:333
spec/features/custom/probe_option_comments_spec.rb:298

One of the custom problems comes from ajax:success[1] not being
triggered, instead only ajax:complete seems to be triggered

We should remove this custom implementation and use the standard
solution provided in rails[2]

[1]
https://github.com/AyuntamientoMadrid/consul/blob/master/app/assets/java
scripts/prevent_double_submission.js.coffee#L28

[2]
https://stackoverflow.com/questions/9570912/how-to-disable-a-form-submit
-button-a-l%C3%A0-ruby-on-rails-way/9572893#9572893

app/assets/javascripts/prevent_double_submission.js.coffee

@@ -22,11 +22,15 @@ App.PreventDoubleSubmission =
 
   initialize: ->
     $('form').on('submit', (event) ->
-      unless event.target.id == "new_officing_voter" || "admin_download_emails"
+      unless event.target.id == "new_officing_voter" || 
+             event.target.id == "admin_download_emails"
+
         buttons = $(this).find(':button, :submit')
         App.PreventDoubleSubmission.disable_buttons(buttons)
     ).on('ajax:success', (event) ->
-      unless event.target.id == "new_officing_voter"
+      unless event.target.id == "new_officing_voter" || 
+             event.target.id == "admin_download_emails"
+             
         buttons = $(this).find(':button, :submit')
         App.PreventDoubleSubmission.reset_buttons(buttons)
     )