SPARK-1537: Add integration with Yarn's Application Timeline Server

A library for integrating Apache Spark with the Apache Hadoop YARN Timeline Server and

This the code behind SPARK-1537, Add integration with Yarn's Application Timeline Server, pulled out into its own repo while the PR awaits review and incorporation.

While standalone, to build it, the repo needs to go in under spark/; the root POM and that of the spark-assembly patched to include it.

License: ASF, obviously

Apache Hadoop and Apache Spark are registered trademarks of the Apache Software Foundation.