kiji-express: EXP-279. Make the paging option for ColumnRequestInput more extensible.

issue: https://jira.kiji.org/browse/EXP-279
review: https://review.kiji.org/r/1327
commit: https://github.com/kijiproject/kiji-express/commit/d111c8d6aa2a3af06f8c983db7000dc8f1f89bea