GUID email responses [RD-93]

Sends job description (if a job is in Solr), job title (if not in Solr but is in database), or an error message (if valid guid but nothing is in Solr or the database) to the address that sent an email to us.

If the job exists, either in Solr or in the database, a success message is prepended to the email body.

All tests pass.