Add unit tests to SQL exception mappers in dropwizard-jdbi
Merge pull request #717 from arteam/dbi_tests

Add unit tests to SQL exception mappers in dropwizard-jdbi
Add simple Ruby script to list contributors

The script is using Octokit (https://octokit.github.io/octokit.rb/) to fetch
the contributor information from the GitHub API (https://developer.github.com/v3/).

Refs #500
Update contributors file, fixes #500