kiji-express: EXP-369. Adds KijiColumnFilterSpec.

Also adds NoColumnFilterSpec and mildly reorganizes ColumnFilterSpec.

issue: https://jira.kiji.org/browse/EXP-369
review: https://review.kiji.org/r/1496
commit: https://github.com/kijiproject/kiji-express/commit/caa60003f2d53eda34db3420b58c54211feddd3b