Fix issue when local properties pass from parent to child thread
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.
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
Merge pull request #940 from ankurdave/clear-port-properties-after-tests

After unit tests, clear port properties unconditionally
Merge pull request #941 from ilikerps/master

Add "org.apache." prefix to packages in spark-class
Merge pull request #937 from jerryshao/localProperties-fix

Fix PR926 local properties issues in Spark Streaming like scenarios