U4-5365 - Added support for paging queries at the database level for media

Just following up the last comment on pull request #448 - have applied the same database level paging logic to media.  Note that as far as I can see paged requests for media aren't actually made from the UI - from looking through the Umbraco.Web.UI.Client project - but if they are in future, this amend will mean they will be supported.