add functional tox target

move the contents of the functional test hook into tox for
consistency.

Change-Id: I730f1bb530215ba7c30bf32a1c3bbc16edd5c217
Required-By: https://review.openstack.org/#/c/156676

tox.ini

@@ -25,6 +25,16 @@ commands = python setup.py testr --coverage
 [tox:jenkins]
 downloadcache = ~/cache/pip
 
+[testenv:func]
+setenv = OS_TEST_PATH=tests.functional
+whitelist_externals =
+    coverage
+    rm
+commands =
+    python setup.py testr --coverage --testr-args="--concurrency=1"
+    coverage report -m
+    rm -f .coverage
+
 [testenv:docs]
 commands=
     python setup.py build_sphinx