Test commit karma for Spark git.
Merge remote-tracking branch 'old/master'
Merge remote-tracking branch 'old/master'
Merge remote-tracking branch 'old/master'
Removed repetative import; fixes hidden definition compiler warning.
Merge pull request #929 from pwendell/master

Use different Hadoop version for YARN artifacts.
Explain yarn.version in Maven build docs
Bumping Mesos version to 0.13.0
Merge pull request #931 from pwendell/yarn-docs

Explain yarn.version in Maven build docs
Merge pull request #932 from pwendell/mesos-version

Bumping Mesos version to 0.13.0
Fix typo in Maven build docs
Merge pull request #933 from jey/yarn-typo-fix

Fix typo in Maven build docs
Merge branch 'master' of github.com:mesos/spark
Fix issue when local properties pass from parent to child thread
Fix issue with spark_ec2 seeing empty security groups

Under unknown, but occasional, circumstances, reservation.groups is empty
despite reservation.instances each having groups. This means that the
spark_ec2 get_existing_clusters() method would fail to find any instances.
To fix it, we simply use the instances' groups as the source of truth.

Note that this is actually just a revival of PR #827, now that the issue
has been reproduced.
Merge pull request #938 from ilikerps/master

Fix issue with spark_ec2 seeing empty security groups
After unit tests, clear port properties unconditionally

In MapOutputTrackerSuite, the "remote fetch" test sets spark.driver.port
and spark.hostPort, assuming that they will be cleared by
LocalSparkContext. However, the test never sets sc, so it remains null,
causing LocalSparkContext to skip clearing these properties. Subsequent
tests therefore fail with java.net.BindException: "Address already in
use".

This commit makes LocalSparkContext clear the properties even if sc is
null.
Merge branch 'master' of github.com:mesos/spark
Add "org.apache." prefix to packages in spark-class

Lacking this, the if/case statements never trigger on Spark 0.8.0+.
Add barrier for local properties unit test and fix some styles