bump health_manager: bulk_api improvements

shortlog:

Bob Nugmanov (1):
      fix: bulk_api loop duration calculation

Bob Nugmanov, David Sabeti and Max Brunsfeld (1):
      bulk API retry logic

Matt Reider (1):
      Update README.md

Change-Id: I435e6536411f5952d89755b3e7ba8b8737dcf18c
Merge git://github.com/cloudfoundry/cf-release