Update __version__

Author: r4fek

django_cassandra_engine/__init__.py

@@ -2,7 +2,7 @@
 # -*- coding: utf-8 -*-
 
 # Do not forget to change version number in mkdocs.yml also!
-__version__ = (1, 6, 3)
+__version__ = (1, 9, 0)
 __author__ = "Rafał Furmański"
 __contact__ = "r.furmanski@gmail.com"
 __homepage__ = "http://github.com/r4fek/django-cassandra-engine"