title: parallelize() method while using SparkSession in Spark 2.0
body: <p>I see that <code>SparkSession</code> doesn't have <code>.parallelize()</code> method, Do we need to use <code>SparkContext</code> again to create a RDD?. If so, is creating both <code>SparkSession</code> &amp; <code>SparkContext</code> in a single program advisable? </p>