Coderedcms

New Features:
* Updated to Wagtail 2.2
* Updated docs to include stability warning

Bug Fixes:
* Fixed issue where default templates generated invalid AMP syntax.
* Multiple child classes can now be created from abstract CoderedArticlePage

Upgrade considerations:
* You may need to run `makemigrations` in your project to update models inheriting from CoderedArticlePage. The related_name for the author attribute has changed.

Bug Fixes:
* `ButtonBlock` will now attempt to render documents in browser.

New Features:
* Added `ReusableContent` snippet with full streamfield content, which can be inserted on multiple pages using a snippet chooser block.

Features
- Added a `ContentWall` snippet. This can be used to add a paywall or an age gate, or any sort of pop up.

Bug Fixes
* Django version is now locked to the same version that Wagtail supports. This will prevent an error where Django 2.1 could be installed when it is not supported by Wagtail.

Initial public release.