Creating a new group dialog is closed on enter without any action

[flekschas]

Steps to reproduce

1. Go to https://refinery-dev.stemcellcommons.org/collaboration/
2. Click on plus
3. Enter whatever name and hit enter.

Observed behavior

Dialog closes without any actions being triggered.

Expected behavior

A new group should be created.

Related code: https://github.com/parklab/refinery-platform/blob/develop/refinery/ui/source/js/collaboration/controllers/add-group.js#L35

The issue is that any error other than an empty name is regarded as a name duplication at the moment. The API would need to provide some information so that the front end can display a meaningful error message.