kiji-express: EXP-236. Local mode test(s) fail non-deterministically with a ZooKeeper "node already exists" exception.

 - Switch to JUnit runner.
 - Remove ScriptRunnerSuite (ScriptRunner is deprecated and being removed/replaced).
 - Non-deterministic behavior is likely caused by SCHEMA-581.

issue: https://jira.kiji.org/browse/EXP-236
review: https://review.kiji.org/r/1220
commit: https://github.com/kijiproject/kiji-express/commit/05a35c68eb2eec3414179576f7cc661707dd3e21