pagination: avoid counting pages outside searches.

Replace this common pattern in controllers:

    @tags = Tag.search(search_params).paginate(params[:page], :limit => params[:limit], :search_count => params[:search])

with this:

    @tags = Tag.paginated_search(params)

`search_count` is used to skip doing a full page count when we're not
doing a search (on the assumption that the number of results will be
high when not constrained by a search). We didn't do this consistently
though. Refactor to do this in every controller.

app/controllers/artist_urls_controller.rb

@@ -3,7 +3,7 @@ class ArtistUrlsController < ApplicationController
   before_action :member_only, except: [:index]
 
   def index
-    @artist_urls = ArtistUrl.includes(:artist).search(search_params).paginate(params[:page], :limit => params[:limit], :search_count => params[:search])
+    @artist_urls = ArtistUrl.includes(:artist).paginated_search(params)
     respond_with(@artist_urls) do |format|
       format.json { render json: @artist_urls.to_json(include: "artist",) }
       format.xml { render xml: @artist_urls.to_xml(include: "artist", root: "artist-urls") }