Setup admin "edit emails" post stylesheet

Setup stylesheet for the admin “edit emails” post screen. Moved inline
styles to stylesheet.
Added email headers meta box

Added email headers meta box after the title. Right now includes the
“from name”, “from email”, “reply to name”, and “reply to email” meta
fields. Updated send_ua_eng_email() to get the fields as default
“from_name”, “from_email”, “reply_to_name”, and “reply_to_email”
arguments.
Fixing .full-width class

Changed .full-width to .ua-eng-emails-full-width so it can be used
outside the fields table.
Beefing up the students communicator template

Adding to and customizing the students communicator template. Adding
lots of style variables and the footer.
Moved iframe styles to stylesheet

Moved iframe styles to stylesheet and moved preview meta box to ‘high’
priority so it will be below the post editor.
Fleshed out more of the communicator template

Added the banner and header image. Setup header image size and am
pulling the header from post featured image, with default in place.