Add the new body classes

closes #1967

- adds paged to eventually replace archive-template
- adds page-template to eventually replace page
- changes custom page template class to be page-slug instead of
  page-template-slug
Return leading image for {{content words="0"}}

Closes #3884
- This PR includes a reimplementation of Downsize@0.0.5 with `words: "0"`. It uses the same parsing methods, therefore guarunteeing identical behavior.
- Tests have been updated to be more extensive.
First pass refactor of GUI readme redux
Fix notification styles

No issue

I'm not sure why, but @extend's here using placeholder selectors, not classes, work.

This fixes the notification and modal styles, which meant changing how the default button selector works. It is now a placeholder, and a real class extends that. The modal styles extended the default button style, which can now happen.
Implements new Configuration API

closes #3619
- adds new permissions for configuration API
- adds integration tests
- adds configuration API for reading allowed values
Merge pull request #3905 from PaulAdamDavis/fix-extends

Fix notification styles
Restrict uncapitalise middleware for API

no ref
- Do not lowercase anything after /api/v0.1/<resource>/ to protect :key/:slug
Merge pull request #3898 from halfdan/fix-uncap-api

Restrict uncapitalise middleware for API
Merge pull request #3841 from halfdan/3619-configuration-api

Implements new Configuration API
Fix regex from #3898

refs #3898
Merge pull request #3906 from halfdan/patch-1

Fix regex from #3898
Merge pull request #3903 from JohnONolan/gui-readme

First pass refactor of GUI readme redux
Merge pull request #3888 from felixrieseberg/iss3884-content

Return leading image for {{content words="0"}}
Add alternative names for pg

refs #3864
- map alternative valid pg names to pg
Resets the scroll position on controller content change

When scrolling through the preview of a long article, if the
post was changed the scroll position of the preview would
remain the same.
Fix user cover images

No issue

The cover image method in the settings/user controller returned the correct asset URL, but not the corresponding CSS which is needed to show it correctly.
Merge pull request #3914 from halfdan/3864-db-config

Add alternative names for pg
Merge pull request #3819 from studioromeo/reset-preview-scroll-position

Reset preview scroll position when post item is clicked
Merge pull request #3934 from PaulAdamDavis/fix-cover-image

Fix user cover images
Remove permissions from configuration API

closes #3909
- Remove permissions from configuration API
- Remove permission setup from integration test
- Remove permissions from permissions.json