Allow include images on newsletters

[decabeza]

Description

It would be nice to allow include images on newsletters sent from admin.

I've started a PR on another fork with the following changes, but I'm stuck on the last one: 😓

1. Change the newsletters form adding the class "admin" on class: "html-area admin" %> to show the images button.

2. Change the newsletter view so the images renders correctly, replacing:

<%= auto_link_already_sanitized_html wysiwyg(@newsletter.body) %> 

to:

<%= auto_link_already_sanitized_html AdminWYSIWYGSanitizer.new.sanitize(@newsletter.body) %> 

3. Finally it would be necessary to change the path in ckEditor so that the image use an absolute path instead of a relative path so that they work from an external site, an email in this case.

In version 1.4.1. I could change the file ckeditor/picture.rb and add in URL the Setting["url"], something like:

url: "#{Setting["url"]}/ckeditor_assets/pictures/:id/:style_:basename.:extension

But I've seen that currently that file ckeditor/picture.rb is very different. 😅

Where could we change that URL value for ckEditor images? 🤔

If someone helps me to solve my doubt 🤞 I can send a PR to add this to CONSUL. 😌

[javierm]

@decabeza I think adding "#{Setting["url"]}#{ to the beginning of the url_content method would solve the problem 🤔. Absolute URLs and emails are tricky, so I'm not sure right now.