Merge pull request #306 from fabaff/kali

Upgrade Kali to 2018.4

src/kali.ipxe

@@ -8,7 +8,7 @@ goto ${menu} ||
 :kali
 set os Kali Linux
 menu ${os} - ${arch_a} 
-item rolling ${os} Rolling Edition (2018.3)
+item rolling ${os} Rolling Edition (2018.4)
 choose version || goto kali_exit
 
 :deb_boot_type