Update backup and restore code, adb sideload

Fixed a problem with using make_ext4fs by making its lib
a dynamic lib.
Added ADB sideload zip install feature - no way to cancel it yet.
Improve backup and restore code.
diff --git a/prebuilt/Android.mk b/prebuilt/Android.mk
index 17e2d4a..650a6a0 100644
--- a/prebuilt/Android.mk
+++ b/prebuilt/Android.mk
@@ -39,6 +39,7 @@
 RELINK_SOURCE_FILES += $(TARGET_OUT_SHARED_LIBRARIES)/libflashutils.so
 RELINK_SOURCE_FILES += $(TARGET_OUT_SHARED_LIBRARIES)/libstlport.so
 RELINK_SOURCE_FILES += $(TARGET_OUT_SHARED_LIBRARIES)/libmincrypt.so
+RELINK_SOURCE_FILES += $(TARGET_OUT_SHARED_LIBRARIES)/libext4_utils.so
 ifeq ($(TW_INCLUDE_BLOBPACK), true)
     RELINK_SOURCE_FILES += $(TARGET_RECOVERY_ROOT_OUT)/sbin/blobpack
 endif