Cap bandit for python 2.7 env

bandit 1.6.3 supports only python>=3.5 and stein jobs with python 2.7
are broken when bandit 1.6.3 is being installed.
bandit <1.6.3 supports python 2.7.
We have no constraint for test only libraries so we need to cap it.

doc/requirements.txt and lower-constraints.txt also needs to be
updated to pass the requirements-check and lower-constarints-job
respectively.

Change-Id: Ia8c69501a1362cb08344aa50d00ed184e9f3d49f

doc/requirements.txt

@@ -7,8 +7,8 @@
 # be installed in a specific order.
 openstackdocstheme>=1.18.1 # Apache-2.0
 reno>=2.5.0 # Apache-2.0
-sphinx!=1.6.6,!=1.6.7,>=1.6.2,<2.0.0;python_version=='2.7' # BSD
-sphinx!=1.6.6,!=1.6.7,>=1.6.2;python_version>='3.4' # BSD
+sphinx>=1.6.2,!=1.6.6,!=1.6.7,<2.0.0;python_version=='2.7'  # BSD
+sphinx>=1.6.2,!=1.6.6,!=1.6.7;python_version>='3.4'  # BSD
 
 # The below is rewquired to build testing module reference
 mock>=2.0.0 # BSD

lower-constraints.txt

@@ -29,11 +29,11 @@ eventlet==0.18.2
 extras==1.0.0
 fasteners==0.7.0
 fixtures==3.0.0
-flake8==2.5.5
+flake8==2.6.2
 flake8-import-order==0.12
 futurist==1.2.0
 greenlet==0.4.10
-hacking==0.12.0
+hacking==1.1.0
 idna==2.6
 imagesize==0.7.1
 iso8601==0.1.11
@@ -82,9 +82,9 @@ pika-pool==0.1.3
 Pint==0.5
 positional==1.2.1
 prettytable==0.7.2
-pycodestyle==2.3.1
+pycodestyle==2.0.0
 pycparser==2.18
-pyflakes==0.8.1
+pyflakes==1.2.3
 Pygments==2.2.0
 pyinotify==0.9.6
 pymongo==3.0.2

test-requirements.txt

@@ -10,7 +10,7 @@
 hacking>=1.1.0,<2 # Apache-2.0
 #
 astroid==2.1.0;python_version>='3.0' # LGPLv2.1
-bandit>=1.4.0 # Apache-2.0
+bandit!=1.6.0,>=1.4.0,<1.6.3 # Apache-2.0
 coverage!=4.4,>=4.0 # Apache-2.0
 doc8>=0.6.0 # Apache-2.0
 flake8-import-order==0.12 # LGPLv3