Add states generating venv and use pydot2

Make it easier for others to create the states diagrams
and use a non-broken pydot fork that is actually being
maintained (pydot2).

Change-Id: Ia16c53a513159a8f15c5d7c75e22553dc1273b37

tools/state_graph.py

@@ -22,8 +22,9 @@ top_dir = os.path.abspath(os.path.join(os.path.dirname(__file__),
                                        os.pardir))
 sys.path.insert(0, top_dir)
 
-# To get this installed you may have to follow:
-# https://code.google.com/p/pydot/issues/detail?id=93 (until fixed).
+# To get this installed you have to do the following:
+#
+# $ pip install pydot2
 import pydot
 
 from taskflow.engines.action_engine import runner

tox.ini

@@ -11,6 +11,7 @@ envlist = cover,
     py33,
     py34,
     pylint,
+    update-states
 
 [testenv]
 usedevelop = True
@@ -26,6 +27,12 @@ deps = {[testenv:py27]deps}
 commands = python setup.py build_sphinx
     doc8 doc/source
 
+[testenv:update-states]
+basepython = python2.7
+deps = {[testenv:py27]deps}
+    pydot2
+commands = {toxinidir}/tools/update_states.sh
+
 [tox:jenkins]
 downloadcache = ~/cache/pip