Update hacking for Python3

The repo is Python 3 now, so update hacking to version 3.0 which
supports Python 3.

Fix problems found.

Remove hacking and friends from lower-constraints, they are not needed
for installation.

Change-Id: I9a2a7c6cd9a0dfd02c6193ceca5653431eed3753

lower-constraints.txt

@@ -9,11 +9,9 @@ dulwich==0.15.0
 eventlet==0.18.2
 extras==1.0.0
 fixtures==3.0.0
-flake8==2.5.5
 gitdb==0.6.4
 GitPython==1.0.1
 greenlet==0.4.14
-hacking==0.12.0
 imagesize==0.7.1
 iso8601==0.1.11
 Jinja2==2.10
@@ -36,9 +34,7 @@ oslo.serialization==2.24.0
 oslo.utils==3.33.0
 oslotest==3.2.0
 pbr==2.0.0
-pep8==1.5.7
 pycparser==2.18
-pyflakes==0.8.1
 Pygments==2.2.0
 pyinotify==0.9.6
 pyparsing==2.1.0

test-requirements.txt

@@ -2,7 +2,7 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
-hacking>=1.1.0,<1.2.0 # Apache-2.0
+hacking>=3.0,<3.1.0 # Apache-2.0
 oslotest>=3.2.0 # Apache-2.0
 mock>=2.0.0 # BSD
 fixtures>=3.0.0 # Apache-2.0/BSD

tox.ini

@@ -45,9 +45,9 @@ commands =
 # E123, E125 skipped as they are invalid PEP-8.
 # [H106] Don’t put vim configuration in source files
 # [H203] Use assertIs(Not)None to check for None
-
+# [W504] line break after binary operator
 show-source = True
-ignore = E123,E125
+ignore = E123,E125,W504
 builtins = _
 exclude=.venv,.git,.tox,dist,doc,*lib/python*,*egg,build
 enable-extensions = H106,H203