[Newsletters] Create a custom markup editor with possibility of uploading an unspecified number of images

In preparation of writing custom custom periodical newsletters, we need the ability for our staff to format text, layout content, and embed images. Therefore, we should create an editor with these capabilities either building on top of the automarkup system or as a restricted set of HTML tags.

• Create large text field with HTML/markup syntax
• Live preview of newsletter content to the side
• Upload media button at the bottom, ability to copy embedding links to add to the text field