* update lab002/hadoop-full-mode
   - /usr/bin/java is conflicted with openjdk
     use folder /usr/lib/jvm/java-6-sun instead
   - remove sun-java6-plugin package (which is not required)
   - download only if ${HOME}/hadoop is not exist
   - delete hadoop tarball after extract
   - reduce $HADOOP_HEAPSIZE to 256
   - ignore $HADOOP_CONF_DIR if it existed