[SPARK-10008] Ensure shuffle locality doesn't take precedence over narrow deps

The shuffle locality patch made the DAGScheduler aware of shuffle data,
but for RDDs that have both narrow and shuffle dependencies, it can
cause them to place tasks based on the shuffle dependency instead of the
narrow one. This case is common in iterative join-based algorithms like
PageRank and ALS, where one RDD is hash-partitioned and one isn't.

Author: Matei Zaharia <matei@databricks.com>

Closes #8220 from mateiz/shuffle-loc-fix.