Improve file system layout support

This change is to use 'casper' to run root file system on the memory and
mount additional partitions to it.

Signed-off-by: Dongjin Kim <tobetter@gmail.com>
Change-Id: If1ae4f025a78765313e0fa2807fc97347d5214fc

custom/templates/oem/fixups/S95-fstab

@@ -0,0 +1,6 @@
+#!/bin/sh
+
+cat <<__EOF | tee -a /etc/fstab >/dev/null
+LABEL=app	/var/app/oem	ext4	ro,relatime 0 0
+LABEL=lib	/var/lib/oem	ext4	ro,relatime 0 0
+__EOF

custom/templates/oem/hooks/mount

@@ -1,2 +1,2 @@
-oem_mount 5 var/app/oem
-oem_mount 6 var/lib/oem
+oem_mount 6 var/app/oem
+oem_mount 7 var/lib/oem

custom/templates/oem/overlay/etc/default/overlayroot

@@ -0,0 +1 @@
+/dev/disk/by-label/vendor

custom/templates/oem/packages

@@ -1 +0,0 @@
-odroid-overlayroot

custom/templates/oem/vendor.list

@@ -1 +1,8 @@
-/etc/hostname
+/etc/default/locale
+/etc/environment
+/etc/hosts.allow
+/etc/hosts.deny
+/etc/profile
+/etc/ssh
+/etc/timezone
+/usr/share/netplan