SPARK-1611: Fix incorrect initialization order in AppendOnlyMap

JIRA: https://issues.apache.org/jira/browse/SPARK-1611

Author: zsxwing <zsxwing@gmail.com>

Closes #534 from zsxwing/SPARK-1611 and squashes the following commits:

96af089 [zsxwing] SPARK-1611: Fix incorrect initialization order in AppendOnlyMap
Spark 1490 Add kerberos support to the HistoryServer

Here I've added the ability for the History server to login from a kerberos keytab file so that the history server can be run as a super user and stay up for along period of time while reading the history files from HDFS.

Author: Thomas Graves <tgraves@apache.org>

Closes #513 from tgravescs/SPARK-1490 and squashes the following commits:

e204a99 [Thomas Graves] remove extra logging
5418daa [Thomas Graves] fix typo in config
0076b99 [Thomas Graves] Update docs
4d76545 [Thomas Graves] SPARK-1490 Add kerberos support to the HistoryServer
Merge branch 'master' of github.com:apache/spark into csd-1.0
adding full outer join support

Conflicts:
	core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala
	streaming/src/main/scala/org/apache/spark/streaming/PairDStreamFunctions.scala
update comment in pyspark code