Add support for namespaced models (#13)

We got it, we just need to `demodulize` the `record` alias.

README.md

@@ -44,6 +44,31 @@ class Post::Publisher < ActiveRecord::AssociatedObject
 end
 ```
 
+### Namespaced models
+
+If you have a namespaced Active Record like this:
+
+```ruby
+# app/models/post/comment.rb
+class Post::Comment < ApplicationRecord
+  belongs_to :post
+
+  has_object :rating
+end
+```
+
+You can define the associated object in the same way it was done for `Post::Publisher` above, within the `Post::Comment` namespace:
+
+```ruby
+# app/models/post/comment/rating.rb
+class Post::Comment::Rating < ActiveRecord::AssociatedObject
+  def great?
+    # A `comment` method is generated to access the associated comment. There's also a `record` alias available.
+    comment.author.subscriber_of? comment.post.author
+  end
+end
+```
+
 ### Remove Active Job boilerplate with `performs`
 
 If you also bundle [`active_job-performs`](https://github.com/kaspth/active_job-performs) in your Gemfile like this:

lib/active_record/associated_object.rb

@@ -2,7 +2,7 @@ class ActiveRecord::AssociatedObject
   class << self
     def inherited(klass)
       record_klass   = klass.module_parent
-      record_name    = klass.module_parent_name.underscore
+      record_name    = klass.module_parent_name.demodulize.underscore
       attribute_name = klass.to_s.demodulize.underscore.to_sym
 
       unless record_klass.respond_to?(:descends_from_active_record?) && record_klass.descends_from_active_record?

test/active_record/associated_object_test.rb

@@ -20,6 +20,9 @@ def setup
   def test_associated_object_alias
     assert_equal @post, @publisher.post
     assert_equal @publisher.post, @publisher.record
+
+    assert_equal @comment, @rating.comment
+    assert_equal @rating.comment, @rating.record
   end
 
   def test_associated_object_method_missing_extraction

test/boot/associated_object.rb

@@ -37,7 +37,6 @@ class Post::Comment::Rating < ActiveRecord::AssociatedObject
   kredis_flag :moderated
 
   def great?
-    # TODO: Fix namespaced records generating a :"post/comments" alias instead of `post_comment` or `comment`
-    record.body == "First!!!!"
+    comment.body == "First!!!!"
   end
 end