imagemagick:
 * bump version to [http://www.imagemagick.org/script/changelog.php 6.8.7-8]
 * add a mirror site (always contains the latest version of imagemagick)


git-svn-id: file:///var/svn/freetz/trunk@11331 149334a1-2f27-0410-a3b9-fc62619ac1e6