Add recovery window option a la acts_as_paranoia

This pull request adds a `:dependent_recovery_window` option to make `paranoia` compatible with that feature of [acts_as_paranoid](https://github.com/ActsAsParanoid/acts_as_paranoid).

When recovering records recursively, associated records will only be restored if they were deleted within the recovery window timespan of the parent's deletion time. This is to enable recovery of a record's associations as they existed at the time it was destroyed.

The default recovery window is set to 2 minutes for compatibility with `acts_as_list`.