(maint) Fix spec failures resulting from Facter API changes

Without this patch stdlib tests fail against Facter 2.x and master but
not 1.6.x.

This patch fixes the problem by initializing the example group
differently depending on the version of Facter integrating into the
system.  The adjusted methods are:

 1.x - Facter.collection.loader.load
 2.x - Facter.collection.load

The collection actually implements the load method in both version, it's
simply marked as private in 1.x.

spec/unit/facter/pe_version_spec.rb

@@ -4,8 +4,16 @@ require 'spec_helper'
 
 describe "PE Version specs" do
   before :each do
+    # Explicitly load the pe_version.rb file which contains generated facts
+    # that cannot be automatically loaded.  Puppet 2.x implements
+    # Facter.collection.load while Facter 1.x markes Facter.collection.load as
+    # a private method.
+    if Facter.collection.respond_to? :load
+      Facter.collection.load(:pe_version)
+    else
       Facter.collection.loader.load(:pe_version)
     end
+  end
 
   context "If PE is installed" do
     %w{ 2.6.1 2.10.300 }.each do |version|