Dashboard fixes [Mj-370, MJ-371, MJ-372]

Reduces number of analytics queries by half on the candidate dashboard
Adds users from analytics data to candidate list
Adds description of candidate activity to candidate pages

There is a join that only occurs when the more button is pressed (thanks, @almathew) resulting in fewer users appearing than should. This happens on master as well as this branch. It looks like that may be more involved than this, so I'm putting this up now.

I would put up a screenshot, but any I could take would be full of email addresses. I can demo if desired.

All tests pass.