Support searches returning artists and albums #14
Description
Currently only single songs can be returned by searches. We should also support artists and albums in search results. A type property would tell the different results apart.
Albums and artists should also be addressed by unique IDs that the backend provides us with (artistID or albumID instead of the songID we now have). Clients should additionally be able to perform search queries for a certain albumID or artistID to get songs from that particular album or artist.