Orm/adm agnostic (working with mongoid)

I started adapting it to work with mongoid, like @lekki has already started doing. Then I refactored it to not include active_record, and to be orm/odm agnostic. It should work in a scenario where the user has active_record, mongoid or both, but of course, only one type of DelayedJob::Job defined. 
It should raise an exception if the user has neither mongoid or active_record in his project.
It's the first time I crafted a gem of this sort, dynamic in relation to other libraries, so thoughts, comments or modifications are appreciated :-)