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

commit: https://github.com/kijiproject/kiji-mapreduce/commit/8814df906be5ca9027a6a32a7211134072df68b5
kiji-mapreduce: [maven-release-plugin] prepare release kiji-mapreduce-root-1.2.7

commit: https://github.com/kijiproject/kiji-mapreduce/commit/891beffb5789643bdb172e40ffeded226fa8a9b0