kiji-end-to-end-tests: SCHEMA-905. Update end-to-end test to work when HADOOP_HOME/HBASE_HOME are otherwise set.

issue: https://jira.kiji.org/browse/SCHEMA-905
review: https://review.kiji.org/r/2098
commit: https://github.com/kijiproject/kiji-end-to-end-tests/commit/bf07a4bf48b52ca5a2fd7f783b437d79371cedf4