kiji-express: EXP-466. Minor bugs in express.py's calculation of java options and dist cache path

issue: https://jira.kiji.org/browse/EXP-466
review: https://review.kiji.org/r/2047
commit: https://github.com/kijiproject/kiji-express/commit/af2247245918e782c07d1b3662a8ab8e06012867