tweaks to link for image subsearch 5, a=chris

diff --git a/src/views/helpers/ImagesHelper.php b/src/views/helpers/ImagesHelper.php
index 39beefca6..816ef6926 100644
--- a/src/views/helpers/ImagesHelper.php
+++ b/src/views/helpers/ImagesHelper.php
@@ -58,8 +58,8 @@ class ImagesHelper extends Helper implements CrawlConstants
             if ($image_subsearch) {
                 $query .= '&s=images';
             } else {
-                if (!stristr($query, "media:image")) {
-                    $query .= '%20media:image';
+                if (!stristr($query, "media%3Aimage")) {
+                    $query .= '%20media%3Aimage';
                 }
             }
             ?>