Notebook security issue

As of now with current version of zepplein:

Lets suppose user1 has created Notebook 9 and he has not changed the note permissions.
And the user2 logins, since the Notebook 9 is visible to user2, he can change the
permissions of the user1 note(Notebook 9).
When notebook is created, it is saved in the common directory called 'notebook'.

Requirement:
With the user successful login, the home page shows all the notebook name,
irrespective of his/her access level. It shouldn't be that way, It should show
only his/her notes and the notes which are shared with him/her.

After note creation, the default note permissions for every notes is accessible
to every other user with permissions to read and edit. It should be in other way round.
Only the owner of the notebook must be allowed to change the permissions.
When the user wants to share his/her notes then he/she will be changing the
permission.

For saving the notebook, it should be like ${username}/notebook or notebook/${username}
instead of common directory 'notebook'.