package/imagemagick: security bump version to 7.0.7-27

Fixes CVE-2018-6405 (upstream Github PR 964) and many others:
http://www.imagemagick.org/script/changelog.php



Added license hash.

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>