Update hacking for Python3

The repo is Python 3 now but still tests some older
branches, so update hacking to version 2.0 which
supports Python 2 and 3.

Fix problems found.

Change-Id: I54f1fa0ee72499a740e630bbd3478427babc2ec2

test-requirements.txt

@@ -3,7 +3,7 @@
 # process, which may cause wedges in the gate later.
 
 # Hacking already pins down pep8, pyflakes and flake8
-hacking!=0.13.0,<0.14,>=0.12.0 # Apache-2.0
+hacking>=2.0,<2.1.0 # Apache-2.0
 # remove this pyflakes from here once you bump the
 # hacking to 3.2.0 or above. hacking 3.2.0 takes
 # care of pyflakes version compatibilty.

tox.ini

@@ -32,4 +32,7 @@ commands = {posargs}
 [flake8]
 show-source = True
 builtins = _
+# W504 line break after binary operator
+# E741 ambiguous variable name 'l'
+ignore = W504,E741
 exclude=.venv,.git,.tox,*lib/python*,private,.eggs