[SPARK-4880] remove spark.locality.wait in Analytics

spark.locality.wait set to 100000 in examples/graphx/Analytics.scala.
Should be left to the user.

Author: Ernest <earneyzxl@gmail.com>

Closes #3730 from Earne/SPARK-4880 and squashes the following commits:

d79ed04 [Ernest] remove spark.locality.wait in Analytics

(cherry picked from commit a7ed6f3cc537f57de87d28e8466ca88fbfff53b5)
Signed-off-by: Reynold Xin <rxin@databricks.com>