The "Import New Note" window unexpectedly closes in multi-user env

Steps to reproduce

1. Open Zeppelin UI and click on "Import note" link on start page. You should see "Import New Note" popup.
2. Open another instance of Zeppelin and try to import another note, rename some note or folder or try to create new note.

Expected result

In the first tab nothing should happen.

Actual result

"Import New Note" window in the first Zeppelin tab get closed without any reason.

Business justification

This is not a big deal when Zeppelin used by one user, but it became a problem when there are a lot of users who try to use Zeppelin at the same time.

Root cause

It seems like workflow for that popup was designed in a following way:

1. User opens popup
2. User drags notebook file into the popup
3. Notebook file gets uploaded to Zeppelin backend
4. On success, backend respond with "NOTES_INFO" message with an updated list of available notebooks
5. Message of "NOTES_INFO" type triggers closing of that popup (this happens in note-import.controller.js and websocket-event.factory.js).

And the flaw of this design is that there are a lot of events which can trigger "NOTES_INFO" message to do the update of an info about available notes, so it happens not only after notebook was successfully uploaded through "Import New Note" popup, but also on a lot of other conditions.