bump dropwizard to 0.9.1
bump dropwizard to 0.9.1

There's a migration guide at [1] though it seems that we're not using
anything that needs migrating.

[1]: https://github.com/dropwizard/dropwizard/wiki/Upgrade-guide-0.8.x-to-0.9.x

openregister/openregister-java,openregister/openregister-java,openregister/openregister-java,openregister/openregister-java,openregister/openregister-java