Move Media Hook Implementations out of media.module

Several functions in media.module under the Media Hook Implementations section should be moved to a separate module.

Specifically it looks like at least media_media_register and media_display_user_files functions should be moved (if not the other functions in the same area) to the media_upload module.

Tying into this I have questions on how http://drupal.org/node/33482 and http://drupal.org/node/353458 may affect how the files table is used. I.E. do we flat out want the various modules to deal with the database themselves and be responsible for managing it and providing file lists, or do we at some point want to provide a generic interface using the files table for the simpler modules.