Patch to add edit links under each picture

Issue Summary

Here's a patch that adds an "Edit" link below each thumbnail in a simplegallery (if the logged in user has permission to edit the node type). The edit link goes to the node editor screen. This change helped me out because I wanted to allow the site owner to edit/delete the picture gallery pics, but I didn't want to give him "administer nodes" access to prevent him from accidentally deleting other parts of his site (like pages). Hope this helps.