Revert "Frappe default wallpaper"

This reverts commit ef89f4e91e.

frappe/public/js/frappe/misc/user.js

@@ -30,8 +30,8 @@ frappe.avatar = function(user, large, title) {
 		});	
 }
 
-frappe.ui.set_user_background = function(src, size) {
-	if(!src) src = "assets/frappe/images/ui/wallpaper.jpg";
+frappe.ui.set_user_background = function(src) {
+	if(!src) src = "assets/frappe/images/ui/random-polygons.jpg";
 	frappe.dom.set_style(repl('#page-desktop { \
 		background: url("%(src)s") center center; \
 	}', {src:src}))