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

commit: https://github.com/kijiproject/kiji-model-repository/commit/aec49714ae2f8b2605c086f07915dac9d9e0ba3d
kiji-model-repository: [maven-release-plugin] prepare release kiji-model-repository-root-0.8.0

commit: https://github.com/kijiproject/kiji-model-repository/commit/1a700d031ac1d267ebb06f5a92ff145b69c1fae4