approvals: move post approval endpoint to /post_approvals.

Move the post approval endpoint from `POST /moderator/post/approval` to
`POST /post_approvals`.

app/controllers/moderator/post/approvals_controller.rb

@@ -1,16 +0,0 @@
-module Moderator
-  module Post
-    class ApprovalsController < ApplicationController
-      before_action :approver_only
-      skip_before_action :api_check
-      respond_to :json, :xml, :js
-
-      def create
-        cookies.permanent[:moderated] = Time.now.to_i
-        post = ::Post.find(params[:post_id])
-        @approval = post.approve!
-        respond_with(:moderator, @approval)
-      end
-    end
-  end
-end

app/controllers/post_approvals_controller.rb

@@ -1,5 +1,13 @@
 class PostApprovalsController < ApplicationController
-  respond_to :html, :xml, :json
+  before_action :approver_only, only: [:create]
+  respond_to :html, :xml, :json, :js
+
+  def create
+    cookies.permanent[:moderated] = Time.now.to_i
+    post = Post.find(params[:post_id])
+    @approval = post.approve!
+    respond_with(@approval)
+  end
 
   def index
     @post_approvals = PostApproval.paginated_search(params)