Merge pull request #921 from minrk/traiterror

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-raising bugs in IPython itself, but only during initialization.

Also, deregister crash handler on use to avoid it being triggered recursively/repeatedly.

IPython/frontend/html/notebook/notebookapp.py

@@ -47,6 +47,7 @@ from .handlers import (LoginHandler,
 )
 from .notebookmanager import NotebookManager
 
+from IPython.config.application import catch_config_error
 from IPython.core.application import BaseIPythonApplication
 from IPython.core.profiledir import ProfileDir
 from IPython.zmq.session import Session, default_secure
@@ -264,6 +265,7 @@ class NotebookApp(BaseIPythonApplication):
         # and all of its ancenstors until propagate is set to False.
         self.log.propagate = False
 
+    @catch_config_error
     def initialize(self, argv=None):
         super(NotebookApp, self).initialize(argv)
         self.init_configurables()