If https fails, attempt http for iPXE builds that don't have https support

src/index.html

@@ -1,4 +1,7 @@
 #!ipxe
 ####       boot.netboot.xyz initial loader       ####
 #### see http://netboot.xyz for more information ####
-chain --autofree https://boot.netboot.xyz/menu.ipxe ||
+set conn_type https
+chain --autofree https://boot.netboot.xyz/menu.ipxe || echo HTTPS failed... attempting HTTP...
+set conn_type http
+chain --autofree http://boot.netboot.xyz/menu.ipxe || echo HTTP failed, localbooting...