Update hacking for Python3

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

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

Change-Id: I0800191c29e0cd379826d62b4bf310606c811263

lower-constraints.txt

@@ -9,8 +9,6 @@ docutils==0.11
 dulwich==0.15.0
 extras==1.0.0
 fixtures==3.0.0
-flake8==2.5.5
-hacking==0.12.0
 imagesize==0.7.1
 iso8601==0.1.11
 Jinja2==2.10
@@ -18,7 +16,6 @@ keystoneauth1==3.4.0
 linecache2==1.0.0
 logilab-common==1.4.1
 MarkupSafe==1.0
-mccabe==0.4.0
 mock==2.0.0
 monotonic==0.6
 netaddr==0.7.18
@@ -28,9 +25,7 @@ oslo.i18n==3.15.3
 oslo.serialization==2.25.0
 oslo.utils==3.33.0
 pbr==2.0.0
-pep8==1.7.1
 prettytable==0.7.2
-pyflakes==1.0.0
 Pygments==2.2.0
 pylint==1.9.2
 pyparsing==2.1.0

test-requirements.txt

@@ -1,8 +1,10 @@
 # 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.
-flake8<2.6.0,>=2.5.4 # MIT
-hacking!=0.13.0,<0.14,>=0.12.0 # Apache-2.0
+
+# Hacking pins already flake8 etc version
+hacking>=3.0,<3.1.0 # Apache-2.0
+
 coverage!=4.4,>=4.0 # Apache-2.0
 mock>=2.0.0 # BSD
 stestr>=2.0.0 # Apache-2.0