Better Desktop integration with DBUS

Made better visibility when a request is available

There are differents method for this.
1) use a system command like
- dbus-notify in Linux
- growl in Mac ( or use DBUS port on Mac OS X)
- ?? in windows (or use DBUS port on Win32)
2) implement DBUS directly in GTK client
3) Blink the number of request in status bar (blink are bad)

And implement API interface to extend the possibility (same as XMLRPC on different object)

Usage example:
- Notify the user when a new request arrival
- remote XSane to scan a document, convert in pdf and store it into the DMS
- When call arrived (VoIP) notify the customer, and maybe open a specific dashboard
- Control OpenERP login session with MSR (magnetic strip reader) or Ibutton
- With server action add new action to open another software (ex start audio player and lauch the music select in the form) (OpenERP Jukebox)
- Launch automatic backup on client and store the file on an external hard disk