kiji-express-music: [maven-release-plugin] prepare for next development iteration

commit: https://github.com/kijiproject/kiji-express-music/commit/a30452ca51362b2a5fe882db71ce29c852b1616b
kiji-express-music: [maven-release-plugin] prepare release kiji-express-music-0.12.0

commit: https://github.com/kijiproject/kiji-express-music/commit/9274c2bc0de913897928cfd7e6dfa61e4168ff2c