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

commit: https://github.com/kijiproject/kiji-model-repository/commit/91e2aef041bc27102934f4cfc198146af8d6fdac
kiji-model-repository: [maven-release-plugin] prepare release kiji-model-repository-root-0.7.0

commit: https://github.com/kijiproject/kiji-model-repository/commit/66b33d4277224b4ff9f1a24823c205d13668cbd7