The related object selector had an issue where some selected options

were wrapping is very ugly ways. The implementation of this isn't

particularly pretty or flexible, and we really need to just rebuild it

all on top of a modern system, but for now, this change is going to

allow us to improve the situation.
This adds a couple static items to the selector class, optionTagName

and autoAddClose. This allows subclasses to change the type of tag

which is used for the individual selected items, and to control whether

we append the close/remove action. With these, a subclass can choose

other layouts for the selected items, such as a <table>. Some basic

styles for using tables are included now as well.

Updated the user selector subclass in Review Board to use a table

instead of a list, and saw that lists of selected users that included

very long usernames or real names no longer wrapped in terrible ways.