Add #any? for Rspec 3 support

When running avalon's tests against rspec 3.0.0.beta2, I ran into the following:
     Failure/Error: expect(master_file.mediaobject.reload.parts).not_to include master_file
     NoMethodError:
       undefined method `any?' for #<ActiveFedora::Associations::HasManyAssociation:0x000000100806c8>