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

commit: https://github.com/kijiproject/kiji-express-examples/commit/673a7bd0a1e612ac7f9200f9acd830e7971113df
kiji-express-examples: [maven-release-plugin] prepare release kiji-express-examples-0.12.0

commit: https://github.com/kijiproject/kiji-express-examples/commit/1812585c2a243cfd5d4821ad03b7580584f02777