SPARK-1187, Added missing Python APIs

The following Python APIs are added,
RDD.id()
SparkContext.setJobGroup()
SparkContext.setLocalProperty()
SparkContext.getLocalProperty()
SparkContext.sparkUser()

was raised earlier as a part of  apache/incubator-spark#486

Author: Prabin Banka <prabin.banka@imaginea.com>

Closes #75 from prabinb/python-api-backup and squashes the following commits:

cc3c6cd [Prabin Banka] Added missing Python APIs