GApplication: allow '-' in application ID

By converting it to _ before trying to shove it into an object path.

https://bugzilla.gnome.org/show_bug.cgi?id=652025

gio/gapplicationimpl-dbus.c

@@ -391,6 +391,9 @@ application_path_from_appid (const gchar *appid)
     {
       if (*iter == '.')
         *iter = '/';
+
+      if (*iter == '-')
+        *iter = '_';
     }
 
   return appid_path;