HIVE-7561 - StarterProject: Move from assert to Guava Preconditions.* in Hive on Spark (Chao via Brock) [Spark Branch]

git-svn-id: https://svn.apache.org/repos/asf/hive/branches/spark@1615830 13f79535-47bb-0310-9956-ffa450edef68