Prefer release version meld3 over master from git

tox.ini

@@ -8,7 +8,7 @@ envlist =
 commands =
     python setup.py test -q
 deps =
-    https://github.com/Supervisor/meld3/tarball/master
+    meld3 >= 1.0.0
     mock >= 0.5.0
 usedevelop = true
 
@@ -22,7 +22,7 @@ basepython =
 commands =
     python setup.py nosetests --with-xunit --with-xcoverage --cover-package=supervisor --cover-erase
 deps =
-    https://github.com/Supervisor/meld3/tarball/master
+    meld3 >= 1.0.0
     mock >= 0.5.0
     nose
     coverage