[appindicator] Use better icons

Fixes #250

appindicator_integration/manifest.ini

 [info]
 name: Appindicator integration
 short_name: appindicator_integration
-version: 0.1.6
+version: 0.1.7
 description: This plugin integrates Gajim with the appindicator. You must have python-appindicator (and Gajim obviously) installed to enable this plugin.<br/>
  Rewriten from Ubuntu Ayatana Integration plugin
 homepage: http://trac-plugins.gajim.org/wiki/AppindicatorSupportPlugin

appindicator_integration/plugin.py

@@ -46,9 +46,9 @@ class AppindicatorIntegrationPlugin(GajimPlugin):
 
         self.events = {}
 
-        self.attention_icon  = "tray-message"
-        self.online_icon     = "tray-online"
-        self.offline_icon    = "tray-offline"
+        self.attention_icon  = "mail-unread"
+        self.online_icon     = "user-available"
+        self.offline_icon    = "user-offline"
         self.connected       = 0
 
         self.connect_menu_item = gtk.MenuItem('Connect')