Cleaning up status messages

Corrected error in response code checking when saving a network (IPython
server now returns 200 instead of 204).

Cleaned up error that was being raised from EIN's notification system.
Seems like there is some logic for popping to a buffer once a
notification event first, but to what buffer is unclear so for know I
have disabled that functionality.
Creating and deleting notebooks

Creating and deleting notebooks from the notebooklist buffer is now
funcitonal and supports subdirectories per IPEP 16.