Fix categories page "more" links

Thanks to #1549496: Upgrade project to support 6.x-3.x version of Apachesolr (prep for d.o. upgrade to D7) the code that's supposed to generate the "categories" landing page is all screwed up:

https://drupal.org/project/modules/categories

The "more" links on there used to link to pages like /project/modules?f[0]=im_vid_3:XX which was just a regular module search with a pre-selected module category filter.

Now, these links are going to pages like /project/[category-name] which sometimes collides with a real project, other times is just a 404 or other confusion.

The bug was introduced in commit http://drupalcode.org/project/project_solr.git/commit/82176500

+  if ($items) {
+    // Add the "more" link.
+    $items[] = array(
+      'data' => l(t('More @category', array('@category' => $category_term->name)), 'project/' . $category_term->name),
+      'class' => 'more',
+    );
+  }

Gotta love those giant monolithic "porting" patches that change all sorts of unrelated things. ;)