Changes required to Plone for pat-cookietrigger.

The new mockup pattern **pat-cookietrigger** replaces the old JS in [plone_ecmascripts/login.js](https://github.com/plone/Products.CMFPlone/blob/master/Products/CMFPlone/skins/plone_ecmascript/login.js)

This pull requests contains all markup and Generic Setup changes required to remove login.js and to use pat-cookietrigger.

There's a pull request for the mockup pattern here: https://github.com/plone/mockup/pull/438

See #282

ping @vangheem