Expose job id as a string for ease-of-use
Allow queued jobs to be cancelled, preventing them from running
Use toString instead of toHexString
Use toString instead of toHexString in test
Merge pull request #12 from blackboard/string-id

Expose job id as a string for ease-of-use
Merge pull request #14 from blackboard/cancel-job

Allow queued jobs to be cancelled, preventing them from running