Jenkins build failure on start project

FYI jasonkuster.

See https://github.com/apache/incubator-beam/pull/72 – the travis build runs all phases and passes, but the jenkins build fails in artifact resolution for the starter project. I suspect this is related to one of these:

• Travis uses `mvn install` while Jenkins uses `mvn clean verify`. Maybe one populates the catalog differently, and the old build was only not failing because we have google-cloud-dataflow artifacts in Maven central.

• Jenkins and Travis differ on maven version and have issues related to the `-incubating` tag we added.

Or something else.