(maint) Allow spec tests to be run on Windows

Previously the spec tests could not be run on Windows due to an errant stub
which always enforce unix path separators.  This commit removes the stub as
it is not required.

spec/facterdb_spec.rb

@@ -5,7 +5,6 @@
   describe 'database' do
 
     before(:each) do
-      stub_const("File::PATH_SEPARATOR", ":")
       ENV['FACTERDB_SKIP_DEFAULTDB'] = nil
       FacterDB.instance_variable_set(:@database, nil)
     end