Corrected foreign key parameter placement in the self join example

https://github.com/rails/rails/issues/447
https://rails.lighthouseapp.com/projects/8994-ruby-on-rails/tickets/6759-api-document-incorrect

Revert "Small edit to the if statement simplification for blank? on the Object class. An Object doesn't need to be nil and empty to be blank? just one or the other."

Reason: the original code is correct, see

    !nil && !empty -> !(nil || empty) -> !blank

That said, this example has too many negations
for my linking. Think should be revised to be
more positive and straightforward to read.

This reverts commit a4b6e3d9.

Small edit to the if statement simplification for blank? on the Object class. An Object doesn't need to be nil and empty to be blank? just one or the other.

Update the description of the :path option to #resources to reflect that it sets the actual path, not a prefix. Most instances were already fixed.

Use #remove_possible_method instead

Move sandbox to AR and pass the sandbox as a value. This way, other ORMs like Datamapper can also have their own sandboxing in rails console.