ALEX: YAML TRANSFORM
config: seperate the CoreOS type from CloudConfig

Renamed Coreos to CoreOS while I was at it.
config: use a YAML transform to normalize keys

This removes the problematic two-pass unmarshalling.
reboot-strategy: remove the 'false' value

Since we no longer do a two-stage unmarshal, the 'false' value will no
longer be necessary.
config: change valid tag to use regexp

A regular expression is much more useful than a list of strings.
ALEX: config: add validity check for file permissions

WIP

These need to be double checked
validate: fix printing for non-string values
config: fix parsing of file permissions

WIP - Tests are still broken

These reintroduces the braindead '744' syntax for file permissions. Even
though this number isn't octal, it is assumed by convention to be.