Ensure "Redeploy" button has expected behaviour

Summary: This ensures that the "Redeploy" button correctly restarts all of the builds triggered from the deployment build.  It does this by traversing the build plans and looking for steps that perform 'Run or Wait for Build Plan', and marking the target builds as failed.  When the top-level build restarts (and the 'Run or Wait for Build Plan' builds run again) all of the targets builds will restart due to being in a failed status.

Test Plan: Tested with build plans with 'Run or Wait for Build Step'.

Reviewers: waynea, #koi, lucasr

Reviewed By: #koi, lucasr

Subscribers: lucasr

JIRA Issues: KOI-1012

Differential Revision: https://code.pageuppeople.com/D3562

Risk Rating: 1