Bump minimum hacking version to 0.9.2

Bump minimum hacking version to 0.9.2

Take advantage of newer version hacking to automate a few style checkings.
A change included this hacking update was proposed by OpenStack Proposal Bot
in earlier patch sets (before 19) but somehow it was missed in latter
proposals. (https://review.openstack.org/#/c/96206/)

Modified/New rules in 0.9.2:

Rule changes:
    * Report E129 instead of E125 for visually indented line with same indent
    * as next logical line.
    * Report E265 for space before block comment.
    * Report E713 and E714 when operators ``not in`` and ``is not`` are
    recommended (taken from hacking).
    * Report E131 instead of E121 / E126 if the hanging indent is not consistent
    within the same continuation block.  It helps when error E121 or E126 is
    in the ``ignore`` list.
    * Report E126 instead of E121 when the continuation line is hanging with
    extra indentation, even if indentation is not a multiple of 4.
    - Dropped H901,H902 as those are now in pep8 and enforced by E713 and E714
New rules:
    + H104  File contains nothing but comments
    + H305  imports not grouped correctly
    + H307  like imports should be grouped together
    + H405  multi line docstring summary not separated with an empty line
    + H904  Wrap long lines in parentheses instead of a backslash

These rules (including changed rules) are all disabled in this change if they
caues any pep8 checking failure, and will be turned on in follow-up patches
if considered useful.

Original commit message in openstack/requirements:

Hacking 0.9.1 was out for a while (hacking 0.9.0 had a minor bug in it, so its
blacklisted), and we want to start supporting projects to migrate over
to 0.9.x. Expand the upper bound to allow 0.9.x while still
supporting 0.8.x series so we keep the old version in our mirrors as to
not break anything.

Change-Id: Ifde0a550e7f9c76b0446759e9f690da2b2aafceb