Fixes #3860 - automated discovery provisioning

Replaces https://github.com/theforeman/foreman_discovery/pull/97
> You pass a Rule into execute_auto_provisioning here, but the code in lib/foreman_discovery.rb seems to be expecting a Host (see below).

Yeah, this is still prototype kind of thing. Will finish soon.

-- 
Later,
 Lukas #lzap Zapletal