Use upper-constraints in tox installs

The tox targets do not currently use upper constaints, resulting in
stable branch test runs pulling down newer library versions than what
should be supported for those releases.

This adds upper-constaints for test environment setup.

Change-Id: I1ff164242901a891fb45da03b1595b2e9246a765
Closes-bug: #1596246

tox.ini

@@ -6,7 +6,7 @@ envlist = py34,py27,pep8
 [testenv]
 setenv = VIRTUAL_ENV={envdir}
 usedevelop = True
-install_command = pip install {opts} {packages}
+install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
 whitelist_externals = find
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
@@ -15,6 +15,10 @@ commands =
   ostestr {posargs}
 
 [testenv:releasenotes]
+# NOTE(jaegerandi): This target does not use constraints because
+# upstream infra does not yet support it. Once that's fixed, we can
+# drop the install_command.
+install_command = pip install -U --force-reinstall {opts} {packages}
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees \
          -b html releasenotes/source releasenotes/build/html
 
@@ -55,12 +59,20 @@ commands =
   oslo-config-generator --config-file etc/oslo-config-generator/manila.conf
 
 [testenv:venv]
+# NOTE(jaegerandi): This target does not use constraints because
+# upstream infra does not yet support it. Once that's fixed, we can
+# drop the install_command.
+install_command = pip install -U --force-reinstall {opts} {packages}
 commands = {posargs}
 
 [testenv:docs]
 commands = python setup.py build_sphinx
 
 [testenv:cover]
+# NOTE(jaegerandi): This target does not use constraints because
+# upstream infra does not yet support it. Once that's fixed, we can
+# drop the install_command.
+install_command = pip install -U --force-reinstall {opts} {packages}
 commands = {toxinidir}/tools/cover.sh {posargs}
 
 [testenv:fast8]