Amarok urls, first (working) draft

[Nikolaj Hald Nielsen]

> amarok://playback/librivox/Shakespeare/King Lear/position:4.10

I really want to enable these urls to enable direct playback of a
track from a service of which this is an extension), but we need a way
to uniquely identify track, which might be service dependent, so how
this url should be constructed will require some thought.

- Nikolaj