Download fluo-cluster JAR file with all dependencies

This module contains all code necessary to run Fluo on a YARN cluster using Apache Twill. It was separated from fluo-core to keep dependencies (like Twill) out of Fluo clients which depend on the fluo-core jar. It was also done to limit conflicts. For example, Twill requires logback to be used but fluo-core requires log4j (due to zookeeper requiring it in accumulo-minicluster).