Change default implementation of to_status to noop
Currently to_status method (https://github.com/theforeman/foreman/blob/f5bfce8bc5cab43fa66c362d40ee843e0783fe72/app/models/host_status/status.rb#L29) of status subclasses throws an exception if not implemented.
There are cases that need external event to happen in order to determine the correct status for a host. For such cases to_status method is unnecessary, and probably won't be implemented. We need to change the default implementation to noop