These reintroduces the braindead '744' syntax for file permissions. Even
though this number isn't octal, it is assumed by convention to be. In
order to pull this off, coerceNodes() was introduced to try to
counteract the type inferrencing that occurs during the yaml
unmarshalling. The config is unmarshalled twice: once into an empty
interface and once into the CloudConfig structure. The two resulting
node structures are combined together. The nodes from the CloudConfig
process replace those from the interface{} when the types of the two
nodes are compatible. For example, with the input `0744`, yaml
interprets that as the integer 484 giving us the nodes '0744'(string)
and 484(int). Because the types string and int are compatible, we opt to
take the string node instead of the integer.
The file permissions can be specified (unfortunately) as a string or an
octal integer. During the normalization step, every field is
unmarshalled into an interface{}. String types are kept in tact but
integers are converted to decimal integers. If the raw config
represented the permissions as an octal, it would be converted to
decimal _before_ it was saved to RawFilePermissions. Permissions() would
then try to convert it again, assuming it was an octal. The new behavior
doesn't assume the radix of the number, allowing decimal and octal
input.
