Remove spark-dependencies module

spark-dependencies module is used for pseudo spark mode which has limited functionality compared to the standard spark mode (launched by spark-submit). At the very beginning, pseudo spark mode is for the new zeppelin users, so they don't need to do any configuration to use spark interpreter.

But now for zeppelin new users, we would suggest they use docker to try spark on zeppelin. So I don't think it is necessary to keep spark-dependencies any more.