RHEL fixes.
Split cart and node tests. Increased timeout for puppet script.
Add SCL dependencies for RHEL builds.
Work around broken rc.local script on ec2 RHEL images
Fix short flag for cartridge tests.
Update README for sync
Merge pull request #4 from pmorie/docs

Update README for sync
Binary artifact suport
Adding CentOS support and making it default OS
Added some cleanup code for clearing yum cache and network settings when creating stage images