Associations: method override logic improvement, and added spec tests for method overriding. Closes #21.
Associations: method override logic improvement, and added spec tests for method overriding. Closes #21.

- now checks to avoid overriding private methods too.  before it was only public/protected.

- the former rule "it's OK to override a method named :type" has been made narrower: "it's OK to override Object#type".  Note that Object#type gives deprecation warnings so it's really safe to override.

dmeranda/schema_associations,budnik/schema_associations