Use subunit-trace from tempest-lib

This makes the test output look like nova's, for consistency.

Change-Id: I24887521d5a3c7d768d77e07e40ab4468e77c9b9

test-requirements.txt

@@ -52,3 +52,6 @@ testscenarios>=0.4
 oslosphinx>=2.2.0  # Apache-2.0
 
 stevedore>=1.1.0  # Apache-2.0
+
+tempest-lib>=0.2.0
+

tools/pretty_tox.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+
+set -o pipefail
+
+TESTRARGS=$1
+python setup.py testr --testr-args="--subunit $TESTRARGS" | subunit-trace -f
+retval=$?
+# NOTE(mtreinish) The pipe above would eat the slowest display from pbr's testr
+# wrapper so just manually print the slowest tests.
+echo -e "\nSlowest Tests:\n"
+testr slowest
+exit $retval

tox.ini

@@ -9,7 +9,7 @@ install_command = pip install -U {opts} {packages}
 setenv = VIRTUAL_ENV={envdir}
 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}'
 whitelist_externals = bash
 
 [testenv:py33]