updater: storage updates for vold-based recovery

Squashed commit of the following:
commit 3fbca42b710b65979c5e77eaddeb88aedff3023a
Author: Pawit Pornkitprasan <p.pawit@gmail.com>
Date:   Wed Aug 28 17:47:47 2013 +0700

    aries-common: updater: fix install from external sd

    Don't use -f with readlink since it won't work if
    the destination does not exist.

    Change-Id: I1e2f16ba009108dbdc69f91202c1dd071c1361e7

commit 498917672bfc93b5abefc94b93a116c884e59bb7
Author: Pawit Pornkitprasan <p.pawit@gmail.com>
Date:   Tue Aug 27 00:21:55 2013 +0700

    aries-common: symlink /external_sd instead of /emmc in recovery

    This is what ROM manager uses

    Change-Id: I64522f48f740d9c16139755e0ea75fdcffc46988

commit cb7657109c4b40056daf50e56ba361353088acf1
Author: Pawit Pornkitprasan <p.pawit@gmail.com>
Date:   Sun Aug 25 13:47:00 2013 +0700

    aries-common: fix installing from stock

    - Package path need to be changed from /sdcard to /storage/sdcard0
    - Readlink does not work on recovery on Samsung ROM

    Change-Id: I28ed95f3ac89ebfc850d5c1be51972cff90d2127

commit 08eb52a09dbaa6494b6714ca196d119b47d238ce
Author: Pawit Pornkitprasan <p.pawit@gmail.com>
Date:   Sun Aug 25 11:15:26 2013 +0700

    aries-common: support vold-based recovery

    Change-Id: I9fc82f8a77a027b10a365aed2411a0cf17d3332d

Change-Id: Iba27fba8800b8283ea146d923ea5b386399bb457