mysql_server_id was going off limits

See: puppetlabs#872

Author: iuriaranda

lib/facter/mysql_server_id.rb

@@ -1,5 +1,5 @@
 def get_mysql_id
-  Facter.value(:macaddress).split(':').inject(0) { |total,value| (total << 6) + value.hex }
+  Facter.value(:macaddress).split(':')[2..-1].inject(0) { |total,value| (total << 6) + value.hex }
 end
 
 Facter.add("mysql_server_id") do