Fixes comment notifications mailers

It was not commendable independent so avery email related with a comment on a proposal was not being sent. Removes dependency on debates and makes it commentable independent.

app/mailers/mailer.rb

@@ -4,23 +4,23 @@ class Mailer < ApplicationMailer
 
   def comment(comment)
     @comment = comment
-    @debate = comment.debate
-    mail(to: @debate.author.email, subject: t('mailer.comment.subject'))
+    @commentable = comment.commentable
+    mail(to: @commentable.author.email, subject: t('mailers.comment.subject', commentable: t("activerecord.models.#{@commentable.class.name.downcase}").downcase)) if @commentable.present? && @commentable.author.present?
   end
 
   def reply(reply)
     @reply = reply
-    @debate = @reply.debate
+    @commentable = @reply.commentable
     parent = Comment.find(@reply.parent_id)
     @recipient = parent.author
-    mail(to: @recipient.email, subject: t('mailer.reply.subject'))
+    mail(to: @recipient.email, subject: t('mailers.reply.subject')) if @commentable.present? && @recipient.present?
   end
 
   def email_verification(user, recipient, token)
     @user = user
     @recipient = recipient
     @token = token
-    mail(to: @recipient, subject: "Verifica tu email")
+    mail(to: @recipient, subject: t('mailers.email_verification.subject'))
   end
 
 end