Don't add AR::Relation unless AR is defined...
Use the API luke...
Use the Ruby API tooooooo
Fully-qualify path to Rails constant
Merge pull request #32 from musicglue/fully-qualify-rails

Fully-qualify path to Rails constant
switch to using class var because we actually want all the subclasses to share the same comparator
merge class var changes with #32
Merge remote-tracking branch 'objects-on-rails/master' into mongoid-support