Download JAR files tagged by zookeeper 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).

ZooKeeper is a centralized service for maintaining configuration information, naming, providing distributed synchronization, and providing group services. All of these kinds of services are used in some form or another by distributed applications. Each time they are implemented there is a lot of work that goes into fixing the bugs and race conditions that are inevitable. Because of the difficulty of implementing these kinds of services, applications initially usually skimp on them ,which make them brittle in the presence of change and difficult to manage. Even when done correctly, different implementations of these services lead to management complexity when the applications are deployed.