kiji-mapreduce: Update versions for Chirashi 1.2.6 release

commit: https://github.com/kijiproject/kiji-mapreduce/commit/fe4a70cd14565c6c79d819282a50648a81156815
kiji-mapreduce-lib: Update versions for Chirashi 1.2.6 release

commit: https://github.com/kijiproject/kiji-mapreduce-lib/commit/313639ade1811052e853141c4ed167fe5977ec90
kiji-express: Update versions for Chirashi 1.2.6 release

commit: https://github.com/kijiproject/kiji-express/commit/b1ae622760d8d6d5ead0c43a4a65c942df349542