add optional parameter to set-alert function in utils package.

This is so I can define what type of alert message I want the server
to send... and include the cat images I found.

src/utils.lisp

@@ -76,11 +76,25 @@ name. Just specify it in this function's `REQUEST-VALUE' argument."
 	       (string= request-value (car item)))
 	  collect item))
 
-(defun set-alert (message)
+(defun set-alert (message &optional alert-type)
   "Sets the alert `MESSAGE' stored in session, provide info. to users.
 The intention is store a `MESSAGE' across a redirect during a HTTP
 POST request."
-  (setf (gethash :alert ningle:*session*) message))
+  (cond ((string= "error" alert-type)
+	 (setf (gethash :alert ningle:*session*)
+	       (build-alert-string alert-type "vomit-cat.png" message)))
+	((string= "success" alert-type)
+	 (setf (gethash :alert ningle:*session*)
+	       (build-alert-string alert-type "disco-cat.png" message)))
+	(t (setf (gethash :alert ningle:*session*) message))))
+
+(defun build-alert-string (alt-text src-image message)
+  (format nil
+	  "<p class=\"~a\"><img alt=\"~a\" src=\"/images/alerts/~a\">~a</p>"
+	  alt-text
+	  alt-text
+	  src-image
+	  message))
 
 (defun get-alert ()
   "Get alert message from session data."