kiji-schema: SCHEMA-838. HBaseKijiRowData fails to create an iterator on an empty unpaged column

issue: https://jira.kiji.org/browse/SCHEMA-838
review: https://review.kiji.org/r/2045
commit: https://github.com/kijiproject/kiji-schema/commit/7d0de8deb01f3d3e040e3b59afaea0fb96427265