Update Running-Spark-on-Tachyon.md

If spark is invoked from environments which can not access core-site.xml, use the SparkContext.hadoopConfiguration.set
Merge pull request #309 from iramaraju/master

Update Running-Spark-on-Tachyon.md
Revert "added todo"

This reverts commit 8b297703cc9c68cd3709e8999d9c09bc1f7b96a7.

Conflicts:

	core/src/main/java/tachyon/util/CommonUtils.java

Signed-off-by: rootfs <hchen@redhat.com>
retain TODO comment for java 6 support

Signed-off-by: rootfs <hchen@redhat.com>
Merge pull request #313 from rootfs/wip-revert-nio

Revert "added todo"