Initial Omnibus/Erchef support (with --distro omnibus-debian).

Currently only supports Ubuntu and Debian platforms but this could be
expanded to Red Hat family distros. All other options remain the same.
add chef-server-redhat template
install ruby, chef, and associated deps
detection for all recognized RHEL platforms
rename redhat template to rhel to match Chef platform_family
fedora isn't part of rhel but enterprise is
rhel: building everything now, still some firewall stuff though.
open the ports we need on the firewall.
remove -x now that I'm no longer debugging things.
update rubygems to avoid some issues with gem activation.
Merge remote-tracking branch 'fnichol/omnibus' into auto-select
first spike of --platform auto support, more coming.
add some comments to auto.sh sourcing and crediting the code.
reorganized templates into a small directory tree. Added a
chef-server-version commandline argument.
red -> green. fully encapsulated distro logic into bootstrap_distro
some deliberate testing of hte auto-selection functionality.
install chef from rubygems based on the version of chef used to run
knife-server.
install net-ssh and friends in a way that keeps rubygems from flipping
out.
set selinux to permissive if necessary
install prerequisites that the gecode-devel package needs to actually
function