July 2014 updates: SLES support and major version bumps.

This patch contains some major environment bumps.

Firstly, it bumps the versions of the major services to:

- Ambari Version 1.6.1
- HDP 2.1
- Hive 0.13
- Tez 0.4.0
- Hadoop 2.4.0.

Secondly, it targets SLES (SUSE Linux Enterprise Server) 11 sp3 AMIs, which support being launched as spot instances. (Previously, the bigdata benchmark used REHL, which did not and still does not support spot.)

Thirdly, it contains some minor fixes / clarifications here and there.

@pwendell @ahirreddy Let me know if this is okay to be merged into master, or into a separate SLES branch.