Builder: intermediate conference webfields should add new entries instead of overwrite the entire webfield

[melisabok]

Instead of overwrite the whole webfield code:

var GROUP_ID = 'MIDL.io/2018';
var HEADER = {
  title: '',
  description: ''
};
var VENUE_LINKS = [
  { url: '/group?id=MIDL.amsterdam/2018/Conference', name: 'MIDL 2018 Conference' },
  { url: '/group?id=MIDL.amsterdam/2018/Abstract', name: 'MIDL 2018 Abstract' },
];

Webfield.ui.setup('#group-container', GROUP_ID);

Webfield.ui.header(HEADER.title, HEADER.description, { underline: true });

Webfield.ui.linksList(VENUE_LINKS);

OpenBanner.welcome();

we should add the new group in VENUE_LINKS. It will help us to fix the MIDL and NIPS new group names.