Use mosaic gallery tpl for Campaign Group

Refs #3474

Uses the `gallery.tpl.php` and `tile.tpl.php` functions for the Campaign Group gallery.

The only thing that's off here is that the`<li>` no longer have the "campaign" or "-published" / "-unpublished" classes.  I am adding the "-unpublished"  class into the `<article>` and not the `<li>`... as its way trickier to get it in the `<li>` .  

Need to look into this with @weerd to figure out whether or not we can use this approach instead of setting the class on the `<li>`

Example: What happens is the gray background is not applied since the "-unpublished" class doesn't live on the `<li>`.

![screen shot 2014-11-20 at 4 06 49 pm](https://cloud.githubusercontent.com/assets/1236811/5133023/8d0ff1aa-70cf-11e4-8fc6-0e766122113c.png)

Once this is approved and merged I will remove the `campaign-gallery.tpl.php` template and functions to close out #3474 and DRY