kiji-express: EXP-470. Add method to profile tuple sizes and operations in express jobs.

issue: https://jira.kiji.org/browse/EXP-470
review: https://review.kiji.org/r/2107
commit: https://github.com/kijiproject/kiji-express/commit/f89b0777234c2ca21b7290301a23cad19ea48398