Support for MEMDISK

The .iso can now be booted using Grub (memdisk from Syslinux package):

	linux16 /memdisk
	initrd16 /path/to/iso

As well as from Syslinux:

	LINUX memdisk
	INITRD path/to/iso

dracut/59-mtd.rules

@@ -0,0 +1,8 @@
+SUBSYSTEM!="block", GOTO="ps_end"
+ACTION!="add|change", GOTO="ps_end"
+# Also don't process disks that are slated to be a multipath device
+ENV{DM_MULTIPATH_DEVICE_PATH}=="?*", GOTO="ps_end"
+
+KERNEL=="mtdblock[0-9]*", IMPORT BLKID
+
+LABEL="ps_end"