Update Testing for Train

Test python 3.7 instead of 3.5 for Train now.
Update docs building to have separate dir for dirtrees so that they do
no get published.

Change-Id: Ica60dc6ffa6c14e0a07489ac8a8b2be4800caa31

.zuul.yaml

@@ -12,8 +12,8 @@
 - project:
     templates:
       - openstack-python-jobs
-      - openstack-python35-jobs
       - openstack-python36-jobs
+      - openstack-python37-jobs
       - check-requirements
       - publish-openstack-docs-pti
     check:

setup.cfg

@@ -16,7 +16,8 @@ classifier =
     Programming Language :: Python :: 2
     Programming Language :: Python :: 2.7
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.5
+    Programming Language :: Python :: 3.6
+    Programming Language :: Python :: 3.7
 
 [files]
 packages =

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 minversion = 2.0
-envlist = py27,py35,pep8,docs
+envlist = py27,py36,py37,pep8,docs
 skipsdist = True
 
 [testenv]
@@ -30,7 +30,7 @@ deps =
     -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
     -r{toxinidir}/requirements.txt
     -r{toxinidir}/doc/requirements.txt
-commands = sphinx-build -W -b html doc/source doc/build/html
+commands = sphinx-build -W -b html -d doc/build/doctrees doc/source doc/build/html
 
 [testenv:debug]
 basepython = python3