Added Cassandra readme
Added Cassandra readme

CloudifySource/cloudify-recipes,ngkim/cloudify-recipes,ngkim/cloudify-recipes,ngkim/cloudify-recipes,ngkim/cloudify-recipes,CloudifySource/cloudify-recipes,CloudifySource/cloudify-recipes,ngkim/cloudify-recipes,CloudifySource/cloudify-recipes,CloudifySource/cloudify-recipes,ngkim/cloudify-recipes,CloudifySource/cloudify-recipes,ngkim/cloudify-recipes