CC-2894: install should check that Virtualenv is functional before proceeding

- install script now check if all python packages are installed, if not,
it will reinstall it

python_apps/python-virtualenv/virtualenv-check.py

@@ -0,0 +1,11 @@
+try:
+    import amqplib
+    import anyjson
+    import configobj
+    import kombu
+    import mutagen
+    import poster
+    import pyinotify
+    print 0
+except ImportError, e:
+    print 1