Add basic history suport and ItemsUpdate
commits 24f02370ef8f4cb8a430b4e48b46fc688b48e1f9, 0d0dfd6af63a7d76b7ea4e4caea2f72ca34299a7 and b4df791263b5540e4416965a6b409cecd3e13ea1 from https://github.com/grooveshark/zabbix