kiji-express: EXP-431. Update KijiExpress to depend on released Scalding 0.9.1

issue: https://jira.kiji.org/browse/EXP-431
review: https://review.kiji.org/r/1774
commit: https://github.com/kijiproject/kiji-express/commit/799f115020746e9232d941dda386995e048103f3