rate limits: adjust limits for various actions.

* Tie rate limits to both the user's ID and their IP address.

* Make each endpoint have separate rate limits. This means that, for
  example, your post edit rate limit is separate from your post vote
  rate limit. Before all write actions had a shared rate limit.

* Make all write endpoints have rate limits. Before some endpoints, such
  as voting, favoriting, commenting, or forum posting, weren't subject
  to rate limits.

* Add stricter rate limits for some endpoints:

** 1 per 5 minutes for creating new accounts.
** 1 per minute for login attempts, changing your email address, or
   for creating mod reports.
** 1 per minute for sending dmails, creating comments, creating forum
   posts, or creating forum topics.
** 1 per second for voting, favoriting, or disapproving posts.
** These rate limits all have burst factors high enough that they
   shouldn't affect normal, non-automated users.

* Raise the default write rate limit for Gold users from 2 per second to
  4 per second, for all other actions not listed above.

* Raise the default burst factor to 200 for all other actions not listed
  above. Before it was 10 for Members, 30 for Gold, and 60 for Platinum.

app/controllers/post_votes_controller.rb

@@ -1,5 +1,4 @@
 class PostVotesController < ApplicationController
-  skip_before_action :api_check
   respond_to :js, :json, :xml, :html
 
   def index