Refactor deployment_deleter
Refactor deployment_deleter

- inline some of the validate method -- it does way more than just
  validate
- extract a parseDeploymentManifest method
- the deferred releaseManager.DeleteAll is weird. We don't want to leave
  extracted releases around because they might be large, but other
  objects have the same releaseManager instance (from the cmd_factory)
  so we have to do the cleanup at the very end (and regardless of
  error). Right now this class is responsible for that cleanup, but
  that's awkward.

  [#93732082]

Signed-off-by: Tyler Schultz <6b7a73f4f7cffc2a148becd12890940350ddfa95@pivotal.io>

allomov/bosh-init,forrestsill/bosh-init,forrestsill/bosh-init,allomov/bosh-init,cloudfoundry/bosh-init,allomov/bosh-init,cloudfoundry/bosh-init,forrestsill/bosh-init,cloudfoundry/bosh-init