Modified script to work with recent API changes, and just use domain name as input

Hi,

Today I tried your LinodeDynDns solution. It looks like the API has changed a bit. I modified your script to work with the new API version. I thought others might be interested in a new version as well.  So here's a pull request.

Also, it's now possible to retrieve the DomainId and ResourceId automatically. Instead of DomainId and ResourceId, the script is now configured with the dynamic domain name (f.e. home.yourname.com)

DomainId is retrieved with domain.list()
ResourceId is retrieved with domain.resource.list()

Linode API link:
https://www.linode.com/api/dns

Kind regards,
andomar@aule.net