Option in the Zeppelin GUI to clear the output in a specific note fro…

[PetroKostyuk]

What is this PR for?

It allowes user to clear notes input from menu. It resolves problem in issue 1503

What type of PR is it?

Feature

What is the Jira issue?

https://issues.apache.org/jira/browse/ZEPPELIN-1503

How should this be tested?

Clicking on new icon should clear output of all notes in given notebook

Screenshots (if appropriate)

[felixcheung]

thanks for the contribution. since this is the notebook menu, it might not be very clear what that icon means or what that "button" does (for example, is it for erasing the notebook? deleting the notebook?) Do you think there is some ways or other places for this?

[PetroKostyuk]

I tought it wold be enought to give it same icon as is used for clearing output in other places. Also, there is tooltip 'clear notes output' on that button, as I have seen in other places in Zeppelin. Sorry i didn't put screenshot of tooltip, i couldn't hover mouse on it same time as selecting area of screenshoot by mouse. But if you have some other idea how to make it clear, I'm opened for suggestions.

[PetroKostyuk]