Categorize community index

There are too many communities on the post-save success screen now. This is a good problem to have, but I'd like to break it up into "Local", "Regional", and "World" tabs, so we're not just showing a big list of stuff, often with multiple facebooks, multiple twitters, etc. We can assign these categories automatically because we know the bounding polygons (and hence areas) for all the communities.

Just some of them: