Upload local previews

Preview files should be able to be added locally if the user wants. Same way the custom banner stuff works only for previews. File selector to select local files or perhaps even online url? Currently there is no way to set or change anything about the previews. This would be done in the media tab of properties. This needs to be done because the previews are not loaded in with whatever is in the image folder and needs to be mapped out in the db!