Update dependency versions for release.
[maven-release-plugin] prepare release kiji-express-music-0.6.0
[maven-release-plugin] prepare for next development iteration
Update dependencies after release.
EXP-181. Make tutorial agree on name of "song_id" field.

This commit fixes a bug in which SongRecommender.scala attempted to
read a field named "songId" from an AvroRecord that should have been
"song_id".

Reviewed by: renuka