* update bin/build_labs_mssql.sh & bin/build_labs_mysql.sh
   - review for generating sample SQL databases and user accounts.
 * add doc/EC2.md
   - how to setup Sqoop + Hive developing environment on AWS EC2
 * update doc/Lab-000.md
   - add NAT ip_forward for Linux node
   - FIX: syntax typo
 * update doc/Makefile
   - remove pdf target