use new facter syntax

Author: zilchms

lib/facter/easyrsa.rb

@@ -5,8 +5,8 @@
   setcode do
     binaryv2 = ''
     binaryv3 = ''
-    operatingsystem = Facter.value(:operatingsystem)
-    operatingsystemrelease = Facter.value(:operatingsystemrelease)
+    operatingsystem = Facter.value(:os)['name']
+    operatingsystemrelease = Facter.value(:os)['release']['major']
 
     case operatingsystem
     when %r{RedHat|CentOS|Amazon}