#7 Add the ability to customize the stream metadata

[Chris Everest]

There are times when we want to rewrite the metadata for a particular stream. Some things to consider

• on a new track, the custom metadata will get overwritten if we simply use server.insert_metadata()
• custom metadata shouldn't interfere with history log, numplays, lastplay (which I don't think it does)
• custom metadata only seems to affect the icecast stream data, which is good. But that means we need and extra display in washtub to show the current custom metadata.
• maybe use a database table tied to user for recent metadata entries. (i.e. 'Chris' new Tracks Show', or 'Sponsored by: ajax cleaning products')

I think the best approach is to use a new panel on the top, to show:

• currently playing (w/custom metadata)
• a toggle switch to apply custom metadata (or let track metadata supersede)
• a button to open a form for modifying the custom metadata
• show actual date/time, time remaining in current track