Simplify rendering flag actions

The `respond_with` method is no longer part of Rails (it's now part of
the responders gem) and we barely use it. Using a template forced us to
use different criteria for different controllers.

This change will also make it easier to fix the flag/unflag actions for
legislation proposals. With the old code, we would have to add another
condition for the legislation/proposals controller.

app/controllers/comments_controller.rb

@@ -35,13 +35,15 @@ class CommentsController < ApplicationController
   def flag
     Flag.flag(current_user, @comment)
     set_comment_flags(@comment)
-    respond_with @comment, template: "comments/_refresh_flag_actions"
+
+    render "comments/_refresh_flag_actions"
   end
 
   def unflag
     Flag.unflag(current_user, @comment)
     set_comment_flags(@comment)
-    respond_with @comment, template: "comments/_refresh_flag_actions"
+
+    render "comments/_refresh_flag_actions"
   end
 
   private