Cap hacking for py2 support

This caps the version of hacking used, and the linters that it ends up
pulling in, to still work with python 2.

Updates the way requirements are installed for the pep8 job to pull in
all test-requirements.

Change-Id: Ifdcb3ca27c50a182c06d9bf39c518a24ea0b3472
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>

test-requirements.txt

@@ -1,6 +1,7 @@
 # The order of packages is significant, because pip processes them in the order
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
+hacking!=0.13.0,<0.14,>=0.12.0,<2 # Apache-2.0
 coverage!=4.4,>=4.0 # Apache-2.0
 fixtures>=3.0.0 # Apache-2.0/BSD
 mock>=2.0.0 # BSD

tox.ini

@@ -31,8 +31,8 @@ usedevelop = False
 skip_install = True
 deps =
     -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
+    -r{toxinidir}/test-requirements.txt
     doc8
-    hacking
     pygments
 commands =
     doc8 doc/source