fix get scala version error #Shark-219#

${SCALA_HOME}/bin/scala -version | awk '{print $5}' will tell us that the version is "Scala code runner version 2.10.3 -- Copyright 2002-2013, LAMP/EPFL"  rather than "2.10.3"  . Consequently,  the condition "if [ "$SCALA_HOME_VERSION" != "$SCALA_VERSION" ] " will never be true.
Extract Tachyon interface to allow pluggable off-heap storage clients
Enable OFF_HEAP caching via "CACHE <table> IN off_heap"
Retitle "tachyon" to "off-heap" everywhere.
Properly handle uncaching/recaching tables
Address Reynold's and Harvey's comments
Address Round # 2 of Harvey's clients
Add comment to SharkEnv re: SHARK_OFFHEAP_CLIENT_FACTORY
Merge pull request #316 from aarondav/master

Extract Tachyon interface to allow pluggable off-heap storage clients
Merge pull request #311 from CrazyJvm/patch-1

fix "get scala version error"  ---  issue #Shark-219#