support marked up mention and return value

It would be nice if you could get all the mention in the text, mark up them, and return them as objects. Like this one:
http://ivirabyan.github.io/jquery-mentions/
This jquery has a method to return values, which are mention objects in the text.
So when I mention people, I can get their ids and notify them easily.

Start by reviewing the repository's client autocomplete entry points and the jQuery mentions example linked in the issue; no repository file or test is named. Clarify the returned mention-object shape and markup behavior, with completion meaning mentions expose their IDs for notification.

Written by the indexing model from the issue text.