Adjust NIBRS bulk download menus

[jeremiak]

To handle the fact that Colorado started submitting NIBRS data in 1992 but then stopped for 1995 and 1996 I added a no-data-years optional array to the UCR program participation data. These years are not included in the year drop down for bulk NIBRS downloads.

Closes 18F/crime-data-explorer#337

This doesn't really mess up any of our other views but does make the introduction text under "Incident details" less accurate. For example, Colorado did not submit incident details/NIBRS data for 1995 or 1996 but if the range 1995-2016 is selected then the sentence reads as follows:

Should we update that view to be more accurate? For example, we could say:

[LarryBafundo]

@jeremiak i like your suggestion, although i would suggest rephrasing "incident details" as either "NIBRS data, or incident data."

While I think it is helpful to explain the time range behind the incident details presented in the Explorer, I wonder if its going to confuse people when we say "this state didn't report incident data for these years" but the trend line on the first half of the page shows an uninterrupted trend. This goes back to some (maybe most?) users won't understand the differences between data types powering the Explorer view.

It's something to test...