Port all classes with inheritance to class framework

All classes that have at least one other derived class (and thus
benefit from the framework) have been now ported. These includes
NMDevice, SearchProvider, AltTab.SwitcherList, and some other
stuff around.

https://bugzilla.gnome.org/show_bug.cgi?id=664436

js/ui/link.js

@@ -4,11 +4,9 @@ const Lang = imports.lang;
 const Signals = imports.signals;
 const St = imports.gi.St;
 
-function Link(props) {
-    this._init(props);
-}
+const Link = new Lang.Class({
+    Name: 'Link',
 
-Link.prototype = {
     _init : function(props) {
         let realProps = { reactive: true,
                           track_hover: true,
@@ -19,6 +17,5 @@ Link.prototype = {
 
         this.actor = new St.Button(realProps);
     }
-};
-
+});
 Signals.addSignalMethods(Link.prototype);