Drop Django 1.11 support

Django 1.11 ends its extended support in April 2020 (which is before
Ussuri release), so horizon drops Django 1.11 support in Ussuri.

tox envs for non-primary Django versions are no longer needed in tox.ini
as testing environments for non-primary Django versions are setup in
the zuul jobs now.

horizon>=17.1.0 is required to use Django 2.2. requirements.txt and
lower-constraints.txt are updated accordingly. for more info. please
refer [1].
Depends-On: https://review.opendev.org/#/c/700733/
[1] https://etherpad.openstack.org/p/Enable_Django22_support_in_Horizon_Plugin

Change-Id: I4f76f7678134ab97abd45b9768ba46d3c77873b3

lower-constraints.txt

@@ -18,7 +18,7 @@ django-appconf==1.0.2
 django-babel==0.6.2
 django-compressor==2.2
 django-pyscss==2.0.2
-Django==1.11.11
+Django==2.2
 docutils==0.14
 dogpile.cache==0.6.5
 dulwich==0.19.0
@@ -28,7 +28,7 @@ fixtures==3.0.0
 flake8==2.5.5
 futurist==1.6.0
 hacking==0.12.0
-horizon==15.0.0.0b1
+horizon==17.1.0
 idna==2.6
 imagesize==1.0.0
 iso8601==0.1.12
@@ -73,10 +73,10 @@ pyOpenSSL==17.5.0
 pyparsing==2.2.0
 pyperclip==1.6.0
 pyScss==1.3.4
-python-cinderclient==3.5.0
+python-cinderclient==5.0.0
 python-glanceclient==2.9.1
 python-heatclient==1.14.0
-python-keystoneclient==3.15.0
+python-keystoneclient==3.22.0
 python-mimeparse==1.6.0
 python-neutronclient==6.7.0
 python-novaclient==10.1.0

requirements.txt

@@ -7,4 +7,4 @@ PyYAML>=3.12 # MIT
 
 python-senlinclient>=1.9.0 # Apache-2.0
 
-horizon>=15.0.0.0b1 # Apache-2.0
+horizon>=17.1.0 # Apache-2.0

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py37,pep8,,py36-local,py3-{dj111,dj22},eslint,karma-local,docs-local,releasenotes,lower-constraints-local
+envlist = py37,pep8,,py36-local,eslint,karma-local,docs-local,releasenotes,lower-constraints-local
 minversion = 2.3.2
 skipsdist = True
 
@@ -11,8 +11,6 @@ deps =
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/test-requirements.txt
 commands =
-  dj111: pip install django>=1.11,<2
-  dj22: pip install django>=2.2,<2.3
   python manage.py test {posargs} --settings=senlin_dashboard.test.settings
 
 # For installation of horizon on local