use favicon config of ala-install

Author: vjrj

grails-app/views/layouts/portal.gsp

@@ -8,7 +8,7 @@
     <meta name="author" content="${grailsApplication.config.skin?.orgNameLong?:'Atlas of Living Australia'}">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <!-- Favicon -->
-    <link href="${grailsApplication.config.skin.favicon}" rel="shortcut icon"  type="image/x-icon"/>
+    <link href="${grailsApplication.config.favicon.url}" rel="shortcut icon"  type="image/x-icon"/>
 
     <title><g:layoutTitle/></title>
     <g:layoutHead/>