admins: remove ability to manually process BURs.

Remove the ability for admins to manually submit BURs without going
through the forum.

app/controllers/admin/alias_and_implication_imports_controller.rb

@@ -1,15 +0,0 @@
-module Admin
-  class AliasAndImplicationImportsController < ApplicationController
-    before_action :admin_only
-
-    def new
-    end
-
-    def create
-      @importer = AliasAndImplicationImporter.new(params[:batch][:text], params[:batch][:forum_id], params[:batch][:rename_aliased_pages])
-      @importer.process!
-      flash[:notice] = "Import queued"
-      redirect_to new_admin_alias_and_implication_import_path
-    end
-  end
-end