(FACT-2874) check for fact_type method before usage
(FACT-2874) check for fact_type method before usage

When sorting resolutions, not all objects respond
to :fact_type(eg Facter::Core::Aggregate does not).
This commit adds a defence to use :fact_type only
for the object that know to respond to it.

puppetlabs/facter,puppetlabs/facter,puppetlabs/facter