Fix belongs_to cmodel inheritance.

[scande3]

While has_many was still working as intended, some changes to
belongs_to broke a cmodel inheritance use case. This use case was
not adequately tested corrected and I've updated the appropriate
unit test to check for the below.

Given the following setup:

class SimpleCollection < ActiveFedora::Base
   has_many :objects, property: :is_part_of, class_name: 'Object'
 end

 class ComplexCollection < SimpleCollection
 end

 class Item < ActiveFedora::Base
   belongs_to :collection, :property=>:is_part_of, \
   :class_name=>''SimpleCollection”
 end

Doing the following should work:

object = Item.new
object.collection = ComplexCollection.create
object.save!

object.collection #returns the complex collection

In our exact use case, we have “SystemCollection” and
“OAICollection” that inherit from a base “Collection”
class. Before this fix, mapping to “Collection” would
return neither despite that being in their cmodel
structure since the code was updated to only look at an
exact class match.

As no one else is using inheritance that I am aware of,
this change should not impact any other hydra heads.

[jcoyne]

Travis isn't finding this. Can you amend the commit message and force-push? Maybe Travis will see it then?

[mjgiarlo]

Travis has been a bit sluggish of late. Looks like the tests passed.

https://travis-ci.org/projecthydra/active_fedora/builds/22730907