Adds shortnames to branding based on cities

Works, but two issues:

1) the shortnames are hard coded into the ui. This is terrible, but i ran out of time and wanted to get something 90% done. Plus, changing the city branding names would require db changes until we built a management widget. All in all, this is a compromise of a solution, which should probably be made way better asap.
2) we also need a few more cities, but I don't know what their slugnames are in the db. Need @threeqube and @christensenep to collude and build that list.

@christensenep can you review and push to staging / prod on Friday? I know this is a bit of a hack, but I want the cities to have custom branding.