kiji-express: EXP-401. Replaces RowSpec with RowRangeSpec and RowFilterSpec.

issue: https://jira.kiji.org/browse/EXP-401
review: https://review.kiji.org/r/1564
commit: https://github.com/kijiproject/kiji-express/commit/ac23e87d937f098d83bdcdb10f45f7cd2a091c08