kiji-schema: SCHEMA-607. Upgrade KijiTableReaderPool to support new ColumnReaderSpec options.

issue: https://jira.kiji.org/browse/SCHEMA-607
review: https://review.kiji.org/r/1541
commit: https://github.com/kijiproject/kiji-schema/commit/81476d6465d2f97fcf1cf0846c5f508424d16ddf