Worked on server.py

/search : Change order to Album.artist
/playlist/<playername>/<place>/up : Change song_id instead of order
Add /playlist/<playername>/<place>/down
Add /playlist/<playername>/<place>/ DELETE
Add /playlist/<playername>/<place>/ PUT

Signed-off-by: Sven Haardiek <Sven@Haardiek.de>