Update revive_destroyed_dependent_records

Use where instead of deprecated method, since Rails 3.2, find(:all, :conditions => {}).

Old/deprecated method resulted in the following error with Rails 4+ and Postgres:
ActiveRecord::StatementInvalid: PG::InvalidTextRepresentation: ERROR:  invalid input syntax for integer: "all"
Merge pull request #36 from eanlain/master

Update revive_destroyed_dependent_records