share setting dialog needs improvements

When user try to share a saved query, some behaviors are not user friendly on this page:
https://westeros.edh.cloudera.com:8888/notebook/notebooks?type=hive

https://westeros.edh.cloudera.com:8888/notebook/editor create the right button: Queries
to review all saved queries the user has. Click on the "share" button to land the "share setting" dialog.

Issues we found on this dialog:
1. When user type in a user name, Press Enter will select that specific top user, but using mouse to select(single click) that user doesn't work as expected, double click on the top user will fill in that user in the text field only, it won't be added to the list as hitting "Enter" button.

2. If we choose a user by hitting "Enter" , by default we set "Read" for the setting. But when user select from the drop down, choose:"Read and Modify", and then click the "+Modify" button, the access for that user can't be updated properly. It seems require to remove the user and choose "Read and Modify" first before clicking on the "+Modify" button or hitting Enter.

3. If we require the user to click on the "+Read"/"+Modify" button before hitting "Done" button, "Done button should be disabled till all mandatory fields are filled.