This does the following to improve deletion failure handling:

- In an UninstallRelease operation, the release is marked DELETED
  as soon as the basic checks are passed. This resolves 1508. I filed a
  followup issue for doing this even better when we can modify protos
  again.
- If a YAML manifest fails to parse, the error messages now suggests
  that the record is corrupt, and the resources must be manually
  deleted.
- If a resource is missing during deletion, the error messages now make
  it clear that an object was skipped, but that the deletion continued.

Closes #1508