was failing in development

Fix new publisher if user is beta

Reshares delegate nsfw to the root post

Use Markerb for emails

Update federation logger

fixes #3120

sad panda.  selenium web driver had to update, and clearly some of the behavior around send_key changed :(

* Add markerb to the Gemfile
* Update mailer classes to send multipart text+html emails
* Simplify all email templates and convert to Markdown+ERB

This required stripping the CSS and images from the emails. All
Markdown templates are based on the original HTML version except
for the inviter, where it was much easier to work with the text
version (and the i18n contains the whole message anyway).

use modulate instead of -brightness-contrast for now, as the cedar stack has an outdated version of mogrify [ci skip]