In order to begin publishing our core SDK package to NPM, we will
need it to be underneath the @pulumi scope so that it may remain
private. Eventually, we can alias pulumi back to it.
This is part of pulumi/pulumi#915.
The two-phase output properties change broke the ability to recover
from a failed replacement that yields pending deletes in the checkpoint.
The issue here is simply that we should remember pending registrations
only for logical operations that *also* have a "new" state (create or
update). This commit fixes this, and also adds a new step test with
fault injection to probe many interesting combinations of steps.
