Simplify deps for logback
Update Storm to 0.9.3
Squelch logging by org.apache.storm.zookeeper.server.NIOServerCnxnFactory in tests

Storm 0.9.3 relocates/shades org.apache.zookeeper to org.apache.storm.zookeeper; cf.
`storm-core/pom.xml` in Storm's code repository:

    <relocation>
        <pattern>org.apache.zookeeper</pattern>
        <shadedPattern>org.apache.storm.zookeeper</shadedPattern>
    </relocation>