Restapi/playlist

Creater restapi for playlist.
For info about restapi:
https://sat.inso.tuwien.ac.at/redmine/projects/qse-ase-ws14-11/wiki/Rest_API_Description

Restapi should be according to:
http://jsonapi.org/format/

I tested it with postman chrome, because at time of development, the infrastructure for mocca was not available
internal server error is http 500