Add posargs to tox

Author: Chris Wacek

tox.ini

@@ -4,7 +4,7 @@ envlist = py27
 
 [testenv]
 install_command = pip install --no-compile {opts} {packages}
-commands = coverage run {envbindir}/nosetests --with-noy --rednose -s
+commands = coverage run {envbindir}/nosetests --with-noy --rednose -s {posargs}
            coverage html --omit=*test* --include=*python_jsonschema_objects*
 deps =
   -rrequirements.txt