acread 0.5.0

When you deprecate an attribute, acread can helps you in 3 ways : 1. helps you finding where you are using this attribute by creating glue to raise a `DeprecatedAttributeError`. 2. ignore this atribute when serializing the object through to_json, to_xml ... 3. helps your zero downtime migration by ignoring the attribute for objects already in memory when saving to database.