bridge (D-Bus): bad design fixes:

- renamed outputed module to dbus_bridge (to avoid uppercase and conflict with dbus module)
    - class name is now Bridge for both frontend and core (make discovery/import more easy)
    - register renamed to register_method in core, and register_signal in frontend

frontends/src/quick_frontend/quick_app.py

@@ -287,7 +287,7 @@ class QuickApp(object):
         if handler is None:
             handler = getattr(self, "{}{}".format(function_name, 'Handler'))
         if not with_profile:
-            self.bridge.register(function_name, handler, iface)
+            self.bridge.register_signal(function_name, handler, iface)
             return
 
         def signalReceived(*args, **kwargs):
@@ -303,7 +303,7 @@ class QuickApp(object):
                         self.signals_cache.setdefault(profile, []).append((function_name, handler, args, kwargs))
                     return  # we ignore signal for profiles we don't manage
             handler(*args, **kwargs)
-        self.bridge.register(function_name, signalReceived, iface)
+        self.bridge.register_signal(function_name, signalReceived, iface)
 
     def addListener(self, type_, callback, profiles_filter=None):
         """Add a listener for an event