controllers: refactor only param includes.

Add extra includes needed by the `only` param inside `respond_with`.

app/controllers/pool_versions_controller.rb

@@ -4,7 +4,9 @@ class PoolVersionsController < ApplicationController
   around_action :set_timeout
 
   def index
-    @pool_versions = PoolArchive.paginated_search(params).includes(model_includes(params))
+    @pool_versions = PoolArchive.paginated_search(params)
+    @pool_versions = @pool_versions.includes(:updater, :pool) if request.format.html?
+
     respond_with(@pool_versions)
   end
 
@@ -27,14 +29,6 @@ class PoolVersionsController < ApplicationController
     "PoolArchive"
   end
 
-  def default_includes(params)
-    if ["json", "xml"].include?(params[:format])
-      []
-    else
-      [:updater, :pool]
-    end
-  end
-
   def set_timeout
     PoolArchive.connection.execute("SET statement_timeout = #{CurrentUser.user.statement_timeout}")
     yield