Creating most google cloud resources uses the compute_operation to
wait for the creation to complete. However, the computeOperationWait*
functions always uses the global `config.Project`, instead of the resource-
specific one.
This means that creating resource in a project other than the main one
fails with a 404 on the operation resource.
This patch uses the project from google_compute_instance instead of the
global one.
This is the first step in removing the config dependency on "project".
This change is backwards-compatible because the value for this new
attribute defaults to the value from the provider.
In order to fix the failing test in the preceding commit when optional
params are changed from their default "computed" values.
These weren't working well with `HttpHealthCheck.Patch()` because it was
attempting to set all unspecified params to Go's type defaults (eg. 0 for
int64) which the API rejected.
Changing the call to `HttpHealthCheck.Update()` seemed to fix this but it
still didn't allow you to reset a param back to it's default by no longer
specifying it.
Settings defaults like this, which match the Terraform docs, seems like the
best all round solution. Includes two additional tests for the acceptance
tests which verify the params are really getting set correctly.
