[SPARK-5157][YARN] Configure more JVM options properly when we use ConcMarkSweepGC for AM.

When we set `SPARK_USE_CONC_INCR_GC`, ConcurrentMarkSweepGC works on the AM.
Actually, if ConcurrentMarkSweepGC is set for the JVM, following JVM options are set automatically and implicitly.

* MaxTenuringThreshold=0
* SurvivorRatio=1024

Those can not be proper value for most cases.
See also http://www.oracle.com/technetwork/java/tuning-139912.html

Author: Kousuke Saruta <sarutak@oss.nttdata.co.jp>

Closes #3956 from sarutak/SPARK-5157 and squashes the following commits:

c15da4e [Kousuke Saruta] Set more JVM options for AM when enabling CMS

yarn/src/main/scala/org/apache/spark/deploy/yarn/Client.scala

@@ -418,6 +418,8 @@ private[spark] class Client(
       // In our expts, using (default) throughput collector has severe perf ramifications in
       // multi-tenant machines
       javaOpts += "-XX:+UseConcMarkSweepGC"
+      javaOpts += "-XX:MaxTenuringThreshold=31"
+      javaOpts += "-XX:SurvivorRatio=8"
       javaOpts += "-XX:+CMSIncrementalMode"
       javaOpts += "-XX:+CMSIncrementalPacing"
       javaOpts += "-XX:CMSIncrementalDutyCycleMin=0"