Show invalid config message on TraitErrors during initialization

implemented via @catch_config decorator

Now, the event that was triggered by invalid app config (see `--log-level 5`) is triggered by bad config at any point during initialization.

This *will* catch TraitError bugs in IPython itself, but only during initialization.

closes gh-908

IPython/frontend/html/notebook/notebookapp.py

@@ -43,6 +43,7 @@ from .handlers import (LoginHandler,
 )
 from .notebookmanager import NotebookManager
 
+from IPython.config.application import catch_config
 from IPython.core.application import BaseIPythonApplication
 from IPython.core.profiledir import ProfileDir
 from IPython.zmq.session import Session, default_secure
@@ -260,6 +261,7 @@ class NotebookApp(BaseIPythonApplication):
         # and all of its ancenstors until propagate is set to False.
         self.log.propagate = False
 
+    @catch_config
     def initialize(self, argv=None):
         super(NotebookApp, self).initialize(argv)
         self.init_configurables()