Show RRs from inactive users on "All Review Requests" and their user page.

Long ago we made a change that hid review requests from inactive users from the
dashboard. Unfortunately, this went way too far, hiding them from all
datagrids, including "All Review Requests" and their user page. As funny as it
is to "disappear" someone when they leave the company, it does make it harder
for people who are trying to find old changes.

Testing done:
* Set a user who had a couple old review requests as inactive. Saw that I could
  now see their changes in /r/ and /users/<user>/. Verified that their pending
  changes were still hidden from my dashboard.
* Ran unit tests.

Fixes bug 1436.

Reviewed at https://reviews.reviewboard.org/r/5488/
Trivial fix for publishing with comma-editable fields and None values.

Comma-editable fields were, by default, wrapping the old and new values
in a set() when checking if the values had changed, in order to do
order-independent comparisons.

However, if the value was None, instead of an empty list, they would
error out. A None value may be perfectly legal for that field, so we
need to allow for this.

This change fixes this by converting None to an empty list when building
the sets.