(FACT-613) Remove interaction with internal loader in legacy processor fact

This commit removes the call to facter.collection.internal_loader.load
in the legacy processor fact, which was redundant with the call to
Facter.value.
(FACT-613) Remove unnecessary confines from legacy processor flat facts

This commit removes unnecessary confines from the legacy processor
flat facts. These facts now resolve their values from the 'processors'
structured fact, which already handles confining.
(FACT-613) Rename keys of processors structured fact

This commit updates the naming of keys within the processors
structured fact to reduce redundancy.
(FACT-613) Convert 'models' key of processors structured fact to array

This commit changes the 'models' key within the processors structured
fact into an array. Previously, the key was a hash which was used
to support the legacy dynamic 'processorX' flat facts. With this
change, the flat fact itself handles its naming based on the index
number of a processor in the array.