Fix maven woes

Fixes issues where some combo of maven & os (3.1.1 w yosemite) is complaining that:

    Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.18:test (default-test) on project brooklyn-api: groups/excludedGroups require TestNG or JUnit48+ on project test classpath -> [Help 1]

also removes some duplicate declared dependencies