Finish Add/Submit Functionality for Adding an Article to a Collection

[bengott]

Rules:

• Owner of collection can add articles directly
• Follower of collection can submit article, then owner can approve to add it to the collection
  • enforce rule that user can only submit his/her own articles?
  • alternative: submitter only needs to be a follower of the collection
    • this could be a good thing for discovery -- lets followers suggest other articles that should be in collection, not just their own

Easier add/submit: HEAD request to retrieve header data from the article url (title, description, date, author, etc.)

• adding/submitting an article could then be as easy as pasting in the url
• this also opens up the possibility of a userscript / browser extension to do it directly from the medium article (submit this article to a collection on extra medium)