nuxeo-popup-permission functional improvements

The Document Permissions section presents some problems.

When you are creating a permission in local permissions:

1. The position of the "Create and Add Another" (centered) is not a pattern.

When you are editing an existing permission in local permissions:

1. There are required fields that are not visually indicated;
2. If you choose "Date-based" option, select the same day both on both date fields and update, the permission disappears from the table;
3. it is possible to hack the notify comment:
   1. Check "Send an email to notify user";
   2. Edit the message;
   3. Uncheck "Send an email to notify user";
   4. Click "Update";
   5. See that the message was stored, even though the notification was disabled.
4. On update, the table renders and creates a flicker;

In permissions assigned to external users:

1. Both email field and date field initial state of is set to error;
2. Place holder text is not styled properly;
3. The position of the "Create and Add Another" (centered) is not a pattern.