kiji-modeling: EXP-303. Remove references to KijiSlice from kiji-modeling.

issue: https://jira.kiji.org/browse/EXP-303
review: https://review.kiji.org/r/1369
commit: https://github.com/kijiproject/kiji-modeling/commit/8388349e916319234eafb06e1c1154baf58cd120