Upgrade to Dropwizard 0.7.1

Upgrade to Dropwizard 0.7.1.
Upgrade newrelic-api from 3.5.0 to 3.72
Upgrade httpclient from 4.3.3 to 4.3.4
Upgrade metrics-core from 3.0.1 to 3.0.2
Upgrade guava from 16.0.1 to 17.0
Clean up Dockerfile

Properly specify an ENTRYPOINT and default CMD
Merge pull request #8 from jplock/jp-dw-7.1

Upgrade to Dropwizard 0.7.1
Merge pull request #9 from jplock/jp-cleanup-dockerfile

Clean up Dockerfile
Use CrossOriginFilter from Jetty 9

Jetty 9 includes various bundled filters, including one to handle CORS.  Let's use that instead of using our own class.
Merge pull request #10 from jplock/jp-jetty-cors

Use CrossOriginFilter from Jetty 9