cloudinit to customspec support

this PR adds a function to parse a user_data cloudinit like string ( as could be sent from foreman) and convert it to an hash usable as customisationspec
If you look at the docs for the method, the `dnsServerList` is supposed to be configured under the `ipsettings` hash.  I'm fairly certain that works and there is code out in the wild relying on that.