Use pretty-tox for better test output

Change-Id: I51465b390fea770f40731fb1c53e13691d49a397

test-requirements.txt

@@ -4,6 +4,7 @@ coverage>=3.6
 discover
 fixtures>=0.3.14
 mock>=1.0
+tempest-lib
 testrepository>=0.0.18
 testscenarios>=0.4
 testtools>=0.9.34

tools/pretty_tox.sh

@@ -0,0 +1,6 @@
+#!/usr/bin/env bash
+
+set -o pipefail
+
+TESTRARGS=$1
+python setup.py testr --slowest --testr-args="--subunit $TESTRARGS" | subunit-trace -f

tox.ini

@@ -11,7 +11,7 @@ setenv =
 deps =
     -r{toxinidir}/requirements.txt
     -r{toxinidir}/test-requirements.txt
-commands = python setup.py testr --slowest --testr-args='{posargs}'
+commands = bash tools/pretty_tox.sh '{posargs}'
 
 [testenv:pep8]
 commands =   flake8 {posargs}