kiji-scoring: SCORE-144. Integrate and validate ColumnReaderSpec behavior in scoring

issue: https://jira.kiji.org/browse/SCORE-144
review: https://review.kiji.org/r/1575
commit: https://github.com/kijiproject/kiji-scoring/commit/d7d9636909ca8934faca2e84781c289cb297eb9c