Move tempest to oslo-config-generator

Also fixes tempest reported bug with old generator in oslo-incubator,
when identical options are registered in different groups.

Change-Id: I274f48503c1b61ca09cabc8d8c50245ba1059943
Closes-bug: 1282887
diff --git a/tox.ini b/tox.ini
index 262a27e..c07dbbf 100644
--- a/tox.ini
+++ b/tox.ini
@@ -19,6 +19,9 @@
        -r{toxinidir}/test-requirements.txt
 commands = bash tools/pretty_tox.sh '{posargs}'
 
+[testenv:genconfig]
+commands = oslo-config-generator --config-file tools/config/config-generator.tempest.conf
+
 [testenv:cover]
 setenv = OS_TEST_PATH=./tempest/tests
 commands = python setup.py testr --coverage --testr-arg='tempest\.tests {posargs}'