Handle ConcurrentModificationExceptions in SparkContext init.

System.getProperties.toMap will fail-fast when concurrently modified,
and it seems like some other thread started by SparkContext does
a System.setProperty during it's initialization.

Handle this by just looping on ConcurrentModificationException, which
seems the safest, since the non-fail-fast methods (Hastable.entrySet)
have undefined behavior under concurrent modification.
Remove SparkHadoopUtil stuff from SparkEnv
Use Properties.clone() instead.
fix sparkhdfs lr test
Merge remote-tracking branch 'upstream/master' into sparkHadoopUtilFix
move the hadoopJobMetadata back into SparkEnv
Avoid match errors when filtering for spark.hadoop settings.
Fixed incorrect log message in local scheduler
Merge pull request #124 from tgravescs/sparkHadoopUtilFix

Pull SparkHadoopUtil out of SparkEnv (jira SPARK-886)

Having the logic to initialize the correct SparkHadoopUtil in SparkEnv prevents it from being used until after the SparkContext is initialized.   This causes issues like https://spark-project.atlassian.net/browse/SPARK-886.  It also makes it hard to use in singleton objects.  For instance I want to use it in the security code.
Merge pull request #126 from kayousterhout/local_fix

Fixed incorrect log message in local scheduler

This change is especially relevant at the moment, because some users are seeing this failure, and the log message is misleading/incorrect (because for the tests, the max failures is set to 0, not 4)
Merge pull request #117 from stephenh/avoid_concurrent_modification_exception

Handle ConcurrentModificationExceptions in SparkContext init.

System.getProperties.toMap will fail-fast when concurrently modified,
and it seems like some other thread started by SparkContext does
a System.setProperty during it's initialization.

Handle this by just looping on ConcurrentModificationException, which
seems the safest, since the non-fail-fast methods (Hastable.entrySet)
have undefined behavior under concurrent modification.
Document all the URIs for addJar/addFile
Add local: URI support to addFile as well
Merge pull request #129 from velvia/2013-11/document-local-uris

Document & finish support for local: URIs

Review all the supported URI schemes for addJar / addFile to the Cluster Overview page.
Add support for local: URI to addFile.
fix persistent-hdfs
Merge pull request #132 from Mistobaan/doc_fix

fix persistent-hdfs
update default github
Fixed a typo in Hadoop version in README.
Merge pull request #134 from rxin/readme

Fixed a typo in Hadoop version in README.
Merge pull request #133 from Mistobaan/link_fix

update default github