Process results on join

[anotherpit]

Currently find() uses processor to cast result records, and join() does not. This PR adds processing to parent records of join() results. Child records still need to be processed.

[devinivy]

@anotherpit I think that makes sense! Do you mind writing a failing test on waterline-adapter-tests?

Also, there's a failing test CI picked-up. I think it's likely a timing issue. Going to re-run the CI. For reference, though, it was:

1) autoIncrement attribute feature should auto generate unique values even when values have been set:
     [Error (E_VALIDATION) 1 attribute is invalid] Invalid attributes sent to undefined:
 • id
   • A record with that `id` already exists (`5`).

[anotherpit]

Moved to #204 to isolate the PR from unrelated changes in my master branch