Allow links to youtube or vimeo as media for a dream

[hspeijer]

• on the 'manage images' screen there will be a text field to add a movie link instead of uploading an image.
• A timecode can also be entered to set the thumbnail image.
• The thumbnail image at timecode is added to s3
• The database must add fields to indicate media is a movie, a url for the playback, platform type (initially youtube or vimeo) and the timecode.
• in manage images the timecode can be updated to set a different thumbnail image for the media.
• in the dream a 'play' button is overlayed on the image.
• if the 'play' button is pressed an overlay is shown with an embedded video player from youtube or vimeo.