data.ref rules don't use optimistic attrs

[dwwoelfel]

This can cause a transaction that creates the attrs referenced in the data.ref to fail with an error: Record not found: attr.

If we used optimistic attrs when evaluating the rules, then this wouldn't happen.

Other ideas:

• Validate that the attrs referenced by data.ref exist before saving the rules
  • But then you'd also have to have some mechanism to alert the developer if they changed attrs in a way that broke the rules.

[nezaj]

@dwwoelfel Including write-up of issue here as well https://paper.dropbox.com/doc/Links-and-Permissions-Error--CXNfqgPDFdPItagxQeOxqJddAg-VVPWfdhYqHThis43aCIeU