* Created TACHYON_CLASSPATH to hold a dynamically generated classpath.
* Updated shell scripts to use TACHYON_CLASSPATH
* Added HADOOP_HOME to point to a local hadoop installation.
* Generate Tachyon + Hadoop CP if HADOOP_HOME is defined
* Updated the default JAVA path in linux to the generic symbolic link (will support most JREs without additional config)
Use a generic method to establish the hadoop classpath.  Requires hadoop command in classpath and works with 1.x and 2.x
Revert the JAVA_HOME setting.
for real revert JAVA_HOME change.
Treat the hadoop classpath as an optional configuration item.  User must uncomment a section in the tachyon-env.sh to add entries for hadoop libraries.
Revert of JAVA_HOME location
Merge pull request #320 from childsb/dynamic_hadoop

Local hadoop install support in tachyon startup scripts