Update USER to PG_USER
Use zooniverse/ruby for Docker build.
Merge pull request #22 from zooniverse/docker-ruby

Use zooniverse/ruby for Docker build.
Add git-core in Docker build.

And some minor tidying in Dockerfile.
Allow specifying database config in yaml.

Converts start_puma to ruby, to allow parsing the production config from
Panoptes.
Bump gems and update expectation syntax
Merge pull request #24 from zooniverse/start-puma-ruby

Allow specifying database config in yaml.
Merge pull request #23 from zooniverse/dockerfile-git

Add git-core in Docker build.
Preserve puma exit code in start_puma
Fix UndefinedTable error
Merge pull request #25 from zooniverse/return-code

Preserve puma exit code in start_puma
Merge pull request #26 from zooniverse/db-id-fix

Fix UndefinedTable error
Parse get_subjects reponse body

Closes #28

+ Include MultiJson as a dependency
+ Bypass Zookeeper setup if ZK_URL is already defined
Merge pull request #29 from zooniverse/better-client-response

Parse get_subjects reponse body
Tidying up
Version bump