0.84/Shell refactoring

Actions

 * Switch to GConf to store the user profile. (erikos)
 * move the matchbox start and the upcoming one of the speech server to the session management
 * Why we can't start the speech server on demand? (using dbus activation). --marco

Plugin systems

 * http://trac.edgewall.org/wiki/TracPlugins
 * http://www.djangoproject.com/documentation/forms/
 * http://twistedmatrix.com/projects/core/documentation/howto/plugin.html
 * http://twistedmatrix.com/projects/core/documentation/howto/choosing-reactor.html