Collections nav item does not work in path mode

[joemull]

Problem

The default collections nav item is created with a leading slash:

janeway/src/cms/models.py

Line 191 in c293d0f

"link": "/collections/%s" % (issue_type.code),

This causes path mode journals to jump to the press level, resulting in a 404.

To replicate:

1. Put a journal in path mode
2. Click "Enable" on the collections nav item in the Content Manager
3. Click on the nav item that is generated
4. See press-level 404

Proposed solution

Generate the URL in a way that will work for both path and domain modes.