Enable H238 hacking rule

Enable H238 hacking rule

Hacking 0.10 introduces new hacking rule H238 - old style classes
are deprecated (they are converted to new style classes - inherit
from `object`). In order to avoid any unwanted side effects all
classes should be declared using new style.

See reference on the differences:
https://www.python.org/download/releases/2.2.3/descrintro/

Change-Id: Iec5620e8f9da2d051a3754391eab4e75faf644e0