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

commit: https://github.com/kijiproject/kiji-express/commit/ff6749fcde2b34b650e5d867b3f69a7b2b3e74e1
kiji-express: [maven-release-plugin] prepare release kiji-express-root-2.0.0-rc1

commit: https://github.com/kijiproject/kiji-express/commit/0d6e68bec7b660286da2af191bccfcc5b5bdb50a