Fixing host resource and provider out-of-sync

From #173 
> The resources/host.rb file contains attributes for groups, templates and interfaces, but those are currently ignored in the providers/host.rb, since that file is only using the parameters[:groupNames], parameteres[:templates] and parameteres[:interfaces] attribute respectively for registering a host to the Zabbix server.

Fixing this issue while I tried to keep the backward compatibility to not brake the agent_registration recipe and other people's application cookbooks using this resource the old way. Could you please review it?