Merge xkb branch.

Squashed commit of the following:

commit 564d267581cff52a6936bdbf318c573cab783f19
Author: Nicolas Boichat <nicolas@boichat.ch>
Date:   Thu May 16 00:30:24 2013 +0800

    Modify existing xkb maps using awk scripts instead of downloading a new package.

commit 4996da3a532a81d7cd0154511a9da94c96b10104
Author: Nicolas Boichat <nicolas@boichat.ch>
Date:   Tue May 14 22:58:31 2013 +0800

    Support for Samsung Chromebook ARM keyboard layout.
Merge clipboard branch.

Squashed commit of the following:

commit 43b5f02974d3e9e62fbfc0975e474d861e726fee
Author: Nicolas Boichat <nicolas@boichat.ch>
Date:   Sat May 25 22:39:40 2013 +0800

    Quiet down croutonclip on startup.

commit e955ffd1ff699cad8833374b01fa60540885572f
Author: Nicolas Boichat <nicolas@boichat.ch>
Date:   Thu May 16 19:46:35 2013 +0800

    Create packaged app (crx file), that is easier to install.

commit e2d757901f17011057209e049ae82da60e7c475d
Author: Nicolas Boichat <nicolas@boichat.ch>
Date:   Tue May 14 19:56:49 2013 +0800

    Make sure that clipboard content is copied over on chroot X server exit.

commit 0085c93168ce9b76af30d248f749785011a3b548
Author: Nicolas Boichat <nicolas@boichat.ch>
Date:   Sun May 12 18:26:32 2013 +0800

    Clearer and more correct variable names in croutonclip.

commit b670fa69f8d33d9acb1cee66b9ae82da2b027279
Author: Nicolas Boichat <nicolas@boichat.ch>
Date:   Sat May 11 15:38:13 2013 +0800

    Install xclip and netcat-openbsd in xephyr target.

commit f59228a2e5cf79ad177b1aab490b1d210024d5a3
Author: Nicolas Boichat <nicolas@boichat.ch>
Date:   Sat May 11 15:09:39 2013 +0800

    Install croutonclip in xephyr target.

commit 9c7d69cf5bbf7eecdfcc982bf7ca8f255a5ed397
Author: Nicolas Boichat <nicolas@boichat.ch>
Date:   Sat May 11 15:08:54 2013 +0800

    croutonclip Chromium OS app: Fix listener.

commit 1193681d3c04aeba890e3e99901943827ae271f3
Author: Nicolas Boichat <nicolas@boichat.ch>
Date:   Sat May 11 15:05:21 2013 +0800

    croutonclip: - Avoid returning non-zero exit status, as it makes
    ratpoison display a warning, and causes artifacts.
    - Check nc command status when copying the clipboard, so that we do not
    erase the chroot clipboard if we do not have any valid content from
    Chromium OS.

commit 53873096fa19c3435ca067e139d76b8c76a73e03
Author: Nicolas Boichat <nicolas@boichat.ch>
Date:   Sat May 11 14:27:27 2013 +0800

    Improved croutonclip. Still a few issues to be sorted out (netcat
    and possible race condition)...

commit 66d5f254d7b8dfdbb45b0c137b1ad295381aef56
Author: Nicolas Boichat <nicolas@boichat.ch>
Date:   Sat May 11 14:18:43 2013 +0800

    Gracefully destroy socket if the window is closed.

commit c81f47b40fe6b0cb9a8e758c38996e68d2d2572e
Author: Nicolas Boichat <nicolas@boichat.ch>
Date:   Sat May 11 13:48:55 2013 +0800

    Improved Chrome OS application: cleaned up code, more sanity checks.

commit 8557209a01446ced8e4e76bce77e1fffa047c7ca
Author: Nicolas Boichat <nicolas@boichat.ch>
Date:   Thu May 9 23:58:35 2013 +0800

    croutonclip guest OS service to handle clipboard transfers.

commit 3e717a07548db1ab3d472a2c9275ec8ae3877ae2
Author: Nicolas Boichat <nicolas@boichat.ch>
Date:   Thu May 9 22:20:30 2013 +0800

    Simple JS-based server to synchronize clipboard between Chrome and crouton.
Merge xbindkeys branch.

Conflicts:
	targets/xephyr