GFR: Add sort logic to creators

[clingerman]

Add sort logic to creators. Try first by "Abolish Date" (putting those with none either first or last). If that is not possible, perhaps just try to sort alphabetically.

[DominicBM]

The sort order is alphabetical now. I think logically, this might be preferable to the end dates, since there are many creators with hierarchies, and alphabetical sorting makes the organizationally similar creators appear in the same area. For example, for RG26, these three will appear in this order:

• Department of Transportation. U.S. Coast Guard. Apalachee (Tug). 4/1/1967-4/11/1986
• Department of Transportation. U.S. Coast Guard. Atlantic Area. Third Coast Guard District. Marine Inspection Office, Philadelphia (Pennsylvania). (7/1973 - 7/1/1987)
• Department of Transportation. U.S. Coast Guard. Atlantic Area. U.S. Coast Guard Maintenance and Logistics Command Atlantic. 1987-3/1/2003

Sorting by end date, these would be in very different parts of the page, and I think it is unclear to the reader how they are sorted.