Alerting in subject of emails when a step in a job fails

Summary:
When a step in a job fails, the hipchat room is alerted, but it still
says jobflow status = SUCEEDED, which is technically true. This change adds a
note that says that a step failed under tha same conditions that cause a
hipchat notification to be sent out, for clarity in hipchat and email subject
lines.

Test Plan:
Tested in python shell looking at jobflow that had sucessful status
but a failed step.

Old subject: Jobflow status = COMPLETED (j-24PGH7FNPSP76: 2013-04-16 GAE Upload)

New subject: Step Failed: Jobflow status = COMPLETED (j-24PGH7FNPSP76: 2013-04-16 GAE Upload)

Reviewers: jace

Differential Revision: http://phabricator.khanacademy.org/D2160
Merge branch 'master' of github.com:Khan/analytics
More informative email alert messages