Remove the unused coding style modules

Python modules related to coding style checks (listed in blacklist.txt in
openstack/requirements repo) are dropped from lower-constraints.txt
as they are not actually used in tests (other than pep8).

Change-Id: Ib2468762d81b0bd694c486169b05b8bbbd142cae

lower-constraints.txt

@@ -2,7 +2,6 @@ alabaster==0.7.10
 appdirs==1.4.3
 APScheduler==3.0.5
 asn1crypto==0.24.0
-astroid==1.3.8
 Babel==2.5.3
 bcrypt==3.1.4
 botocore==1.5.1
@@ -26,10 +25,8 @@ eventlet==0.20.0
 extras==1.0.0
 fasteners==0.14.1
 fixtures==3.0.0
-flake8==2.5.4
 future==0.16.0
 greenlet==0.4.13
-hacking==0.12.0
 idna==2.6
 imagesize==1.0.0
 iso8601==0.1.12
@@ -43,7 +40,6 @@ linecache2==1.0.0
 logilab-common==1.4.1
 libvirt-python==1.2.5
 MarkupSafe==1.0
-mccabe==0.4.0
 mock==2.0.0
 monotonic==1.4
 msgpack==0.5.6
@@ -71,15 +67,12 @@ paramiko==2.0.0
 Paste==2.0.3
 PasteDeploy==1.5.2
 pbr==2.0.0
-pep8==1.7.1
 prettytable==0.7.2
 psutil==3.2.2
 pyasn1==0.4.2
 pycparser==2.18
-pyflakes==1.0.0
 Pygments==2.2.0
 pyinotify==0.9.6
-pylint==1.4.5
 pymongo==3.0.2
 PyMySQL==0.7.6
 PyNaCl==1.2.1

test-requirements.txt

@@ -2,8 +2,6 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
-astroid==1.6.5 # LGPLv2.1
-
 # hacking pins flake8 etc
 hacking>=3.0,<3.1.0  # Apache-2.0
 coverage>=4.0