single issue page doesn't include publication date

[rlskoeser]

I was checking the date for a Startwords piece recently and was surprised that there were no dates on the single issue page (e.g., issue 3. You have to click in to the article to see a date. We do include dates on the issue list page.

There is also no date on the issue as displayed on the homepage — I think @gwijthoff needs to weigh in on whether we want it there or not (my vote is yes).

I propose we add the date to the single issue page using a format and layout similar to what we have on the issue list and article details.

[gwijthoff]

Addressed in #328