remove unnecessary module constraint

Python modules related to coding style checks (listed in blacklist.txt in
openstack/requirements repo) are dropped from lower-constraints.txt
they are not needed during installation.

Change-Id: Iae39b223a627bb4ce370f3cf307570b65a4a05a7

lower-constraints.txt

@@ -25,12 +25,10 @@ eventlet==0.20.0
 extras==1.0.0
 fasteners==0.14.1
 fixtures==3.0.0
-flake8==2.5.5
 future==0.16.0
 futurist==1.2.0
 google-auth==1.4.1
 greenlet==0.4.13
-hacking==0.12.0
 idna==2.6
 ipaddress==1.0.19
 iso8601==0.1.12
@@ -44,7 +42,6 @@ linecache2==1.0.0
 logutils==0.3.5
 Mako==1.0.7
 MarkupSafe==1.0
-mccabe==0.2.1
 monotonic==1.4
 mox3==0.25.0
 msgpack==0.5.6
@@ -73,7 +70,6 @@ Paste==2.0.3
 PasteDeploy==1.5.2
 pbr==2.0.0
 pecan==1.0.0
-pep8==1.5.7
 pika==0.10.0
 pika-pool==0.1.3
 prettytable==0.7.2
@@ -81,7 +77,6 @@ pyasn1==0.4.2
 pyasn1-modules==0.2.1
 pycadf==2.7.0
 pycparser==2.18
-pyflakes==0.8.1
 pyinotify==0.9.6
 PyMySQL==0.7.6
 PyNaCl==1.2.1