add imagick to install if necessary

[joehobson]

I was trying to figure out why this resource has a featured image when I edit it, but doesn't display it on the resource page. Looks like it might have something to do with the use of image_editor, which fails quietly. I installed imagick on the wp-test server (http://php.net/manual/en/imagick.setup.php) and then tried again but still ran into some issues. I don't know that the file URL is getting parsed properly.

To fix this, please add debug log to the use of image_editor, logging if that template is unable to resize the image.

Then test whether we should explicitly require install of imagick and add to the ReadMe if necessary with install instructions. My guess is that we do. You can uninstall imagick on the test server and run with debug to see if it's necessary, then reinstall.

And of course if the image display isn't working due to other issues, get those resolved as well.