Dashboard Server can't display interactive widgets

[codingneo]

I build and install a dashboard server from the current master branch. It works fine. But when I deployed the taxi demo dashboard to this dashboard server, it can't display any interactive widgets. The local dashboard of the same notebook works fine.

[parente]

I'm guessing the support for the declarative widgets regressed after the latest release of that project.

As you can probably tell, we haven't had cycles to spend on keeping the dashboard server up to snuff with the latest versions of all the other jupyter projects.