Better generic error handling

This release allows job_fail to be called with a null/empty second argument, and will report it as 'unhandled_error'.

Change job_ignore function signature

Allow users to pass both a status message and failure reason when ignoring a job

Looser job attachments

v1.2

remove type restriction for job attach method

Job attachments

Merge pull request #13 from envoy/job-attchment

added job_attach method for attachments shown in visitor view