Variable headquarters buffer size for finding associated government units

[meilinger]

In order to more easily find and associate government units with departments in the quest to determine jurisdictional boundaries for departments, we need a mechanism to increase the size of the initial department headquarters buffer size when finding associated government units.

Something as simple as a slider or a numeric input (for distance) would be sufficient.

[meilinger]

As a stop-gap, government unit intersections are done on a 5km buffer from the headquarters geom. see bcb89b0