Collect artifacts for CircleCI

Collect generated Debian packages, and any JAR's that end in a version or
snapshot number (that is, not sources, javadoc, or shaded).
CircleCI: Add parallelism for tests

Also move stuff into circle.sh since it's more complicated now and hard to
express in yaml.
Merge pull request #112 from spotify/rohan/circleci

CircleCI: artifacts and parallel builds