Readers autocomplete should match anyone on the site

[boonebgorges]

I built the Readers autocomplete tool #18 so that it reads from a JS array built on the server, instead of AJAX requests. The array includes the logged-in user's friends, current readers of the paper, and members of all groups the user is a member of. I did it this way because user autocomplete is pretty slow on the Commons, and this way of doing things is much, much faster.

But there will be cases where someone will want to add someone who doesn't fall into one of these categories. I spent some time writing a custom dataAdapter for Select2 - one that would first look in a local array, and then search via AJAX when nothing was found there - but didn't want to go too deep in the rabbit hole for v1. I'm opening this ticket so that I don't forget about it.

[boonebgorges]

See https://gist.github.com/dirnthelord/0384111cfb7f88e7a3e5 and https://redmine.gc.cuny.edu/issues/5320