allow referentials search to use accents

In https://github.com/georchestra/georchestra/blob/master/mapfishapp/src/main/webapp/app/js/GEOR_referentials.js#L250 the queryString sees its accentued letters replaced by their ascii equivalents. Meanwhile, the dbf file on the layer can contain utf-8 encoded accents (such as 'église' or 'côte'), looking for 'église' will send the search with 'eglise' and yield no records. If i comment out that line i'm able to successfully search for accentued entries in the WFS.

I can understand the uppercase thing to match on Église & église though, as long as everything in the dbf is uppercased (including accents!)..