Adding debugger in tox.ini

This PS will add debugger in tox.ini
So it will be easy to check the tests in debug mode
for failure and success too.

Change-Id: I604515a7a5fd369f15c215c75db4a0e91c93ca69
diff --git a/tox.ini b/tox.ini
index 4d3c622..4068054 100644
--- a/tox.ini
+++ b/tox.ini
@@ -48,6 +48,10 @@
   coverage xml -o cover/coverage.xml
   coverage report
 
+[testenv:debug]
+basepython = python3
+commands = oslo_debug_helper -t tempest/tests {posargs}
+
 [testenv:all]
 envdir = .tox/tempest
 sitepackages = {[tempestenv]sitepackages}