parent after_create callback still run when child fails validation

[trungpham]

if the child validation fails, then parent after save and after create callback should never execute.

[snusnu]

I started refactoring the specs a bit mainly to become familiar with all this stuff again. I will try to work through these issues in the next days, but I'd greatly appreciate any help from your side! :) That doesn't necessarily mean that you'd need to send patches to correct the behavior, but failing specs would certainly be appreciated! (of course, patches that fix the errorneous behavior too :)