kiji-scoring: SCORE-106. The kiji scoring server API should accept per-request parameters.

issue: https://jira.kiji.org/browse/SCORE-106
review: https://review.kiji.org/r/1337
commit: https://github.com/kijiproject/kiji-scoring/commit/a5b58b759c19f26073b0f85a7479d03b461eae3d