kiji-schema: SCHEMA-693.  Move classes from impl to impl.hbase.

This refactoring already happened in the Cassandra branch.  Doing this
on master now to make eventual merge with Cassandra easier.

Some classes / interfaces we did not move yet to impl.hbase because they
get used in fake HBase - we will refactor these later, when we do
modifications to other projects.

review: https://review.kiji.org/r/1759
issue: https://jira.kiji.org/SCHEMA-693
commit: https://github.com/kijiproject/kiji-schema/commit/0677a10d166ef8daf4b762f7de587194df78a64a
kiji-mapreduce: KIJIMR-270.  Update schema.impl refs (SCHEMA-693).

review: https://review.kiji.org/r/1781
issue: https://jira.kiji.org/KIJIMR-270
commit: https://github.com/kijiproject/kiji-mapreduce/commit/e097612a9a7feb2b60c783d6e5334c87d9fa27fd