centos6 Initial commit

[sathiyas]

This change enables users to create centos6 based Consul cluster. CentOS.org does not allow launch AMIs directly since it is available only through Market place. The execution will throw an error asking to accept terms and conditions of market place one and provides a link specific to the account that is used to execute. Once you accept the terms, next execution will succeed. Another option is to replace the default AMI with another trusted centos6 AMI, the caveat is it may not be endorsed by centos.org

[sathiyas]

Please see note from centos @ http://wiki.centos.org/Cloud/AWS

“Using the AMI's directly is currently deprecated. We are working to resolve issues and establish automation as well as monitoring around resources and process that will allow us to re-enable direct AMI instantiation. In the mean time, the AMI's are listed at the bottom of this document for legacy / reference purposes."

[sathiyas]

@phinze , the build seems to have failed, I hope it's nothing to do with this pull, please check

[ryanuber]

@sathiyas it's definitely not related to your changes. Unfortunately Consul has a hard time with its unit tests on Travis-CI sometimes.

[armon]

Thanks!