changed path to iso to server specific file path to simplify deployment

vagrant.json

 {
     "variables": {
-        "iso_url": "https://downloads.archlinux.de/iso/{{isotime \"2006.01\"}}.01/archlinux-{{isotime \"2006.01\"}}.01-x86_64.iso",
-        "iso_checksum_url": "https://downloads.archlinux.de/iso/{{isotime \"2006.01\"}}.01/sha1sums.txt",
+        "iso_url": "file:///srv/ftp/iso/latest/archlinux-{{isotime \"2006.01\"}}.01-x86_64.iso",
+        "iso_checksum_url": "file:///srv/ftp/iso/latest/sha1sums.txt",
         "iso_checksum_type": "sha1",
         "disk_size": "20480",
         "memory": "1024",