core, bridge, jp, quick_frontend: SàT stop more gracefully if bridge can't be initialised: - new BridgeInitError and BridgeExceptionNoService are in core.exceptions - D-Bus NotSupported is catched in bridge, and launch a BridgeInitError - BridgeInitError stop SàT core, jp, and quick_frontends with an explanation message. fix bug 27

--- a/src/core/exceptions.py	Thu Jun 20 17:44:27 2013 +0200
+++ b/src/core/exceptions.py	Fri Jun 21 02:00:37 2013 +0200
@@ -44,3 +44,9 @@
 
 class DataError(Exception):
     pass
+
+class BridgeInitError(Exception):
+    pass
+
+class BridgeExceptionNoService(Exception):
+    pass