Hacking package upgraded, code cleaned to enforce new style rules

The hacking package has been upgraded from 'hacking>=0.8.0,<0.9' to 'hacking>=0.9.2,<0.10' to fix bug #1330540 (https://bugs.launchpad.net/designate/+bug/1330540). As such, new style rules have been added to the flake8 tests and must be addressed. Some of these rules will be added to Designate's enforcement, and some will be ignored.

The following rules have been added and are now enforced:
- H236 Python 3.x incompatible __metaclass__, use six.add_metaclass()
- H305 imports not grouped correctly
- H307 like imports should be grouped together
- E111 Indentation is not a multiple of four
- E251 unexpected spaces around keyword / parameter equals
- E265 Block comment should start with '# '

The following rules will be added to the tox.ini ignore list:
- H104 file contains nothing more than comments
- H405 multi line docstring summary not separated with an empty line
- H904 Wrap long lines in parentheses instead of a backslash
- E126 continuation line over-indented for hanging indent
- E128 continuation line under-indented for visual indent