Pin nbdime release compatible with JLab 1.x (#560)

Author: lresende

setup.py

@@ -71,7 +71,7 @@ def runPackLabextension():
     ],
     install_requires = [
         'notebook',
-        'nbdime >= 1.1.0',
+        'nbdime >= 1.1.0, < 2.0.0',
         'pexpect'
     ],
     extras_require = {