Issue-24: Add feature to filter people report by staff / not staff

[wonderificdave]

For Issue-24: #24

[asalant]

This looks like a fine change and I'd be happy to merge it in with a couple minor changes:

1. Add a test to person_test.rb for Person::is_staff. If you look at test_matching_name the pattern should be pretty obvious.
2. Alternately, you could add a controller test to reports_controller_test.rb that covers using the is_staff parameter. If that test works, you know that Person::is_staff is working so I'd be fine without the test in Email address validation sometimes fails when it should not #1 above.
3. For the People report UI, let's add a class to the span for each option and set the width of that class to 30px or something like that to space them out evenly. If you rename "Patrons" to "Patron" it will space slightly nicer too. I'd be happy to make this UI tweak but since you'll be in there already for the above you might as well take care of this.

Something that is nice for pull requests that include UI changes is to include a screenshot in the PR of the change which makes review much easier. A tip/request for next time ;-)

[wonderificdave]

Hi Alon, I checked in the changes and grabbed a screenshot. LMK if you have any thoughts, especially the CSS changes (I'm not really a UI guy).

[asalant]

Looks great. Thanks!