Add 'Categories:' on waterfall page (like console already).
Items in 'Categories:' are click-able links like '/waterfall?category=...'
so they are convenient to filter your waterfall view.
Screenshot:
http://pix.academ.org/img/2014/07/10/40be2295c6e0de74ef17b8e138f5421c.png
Surround 'Categories:' by 'if categories|length > 1' on waterfall page.
Release notes: add item with description 'categories' link on 'Waterfall' page.
Merge pull request #1176 from asashnov/eight

Add 'Categories:' click-able links on waterfall page