[PATCH] docker: Use heredocs where possible

[Petr Vorel]

Hi Stephen,
> This was suggested in a recent review [1]. Make it happen.

> [1] http://patchwork.ozlabs.org/patch/933979/#1941584

> Signed-off-by: Stephen Finucane <stephen at that.guru>
> Suggested-by: Petr Vorel <petr.vorel at gmail.com>
Reviewed-by: Petr Vorel <pvorel at suse.cz>
> ---
LGTM, thanks for taking care for it.

Next step could be to remove bashisms and have it as a posix shell script with
/bin/sh (I can do it).

Kind regards,
Petr