Fix city resolution and test coverage

[ahalterman]

This PR is focused on fixing a bug in city name resolution (#1) with some associated other improvements:

• Resolve Prevent cities being geocoded to things inside the city #1, which deals with cities being resolved to places inside the city, rather than the city itself. This was the result of trying to narrowing the Elasticsearch query using keywords from the vicinity of the place name. Just doing a regular query gives much better results. Future work can figure out if it makes sense to add back in query_geonames_featureclass.
• Move the MITIE entity extraction of /places from the post function to the process function, which makes more sense and makes it easier to test.
• Greatly expand test coverage to include MITIE, query_geonames, and whether cities are correctly resolved.
• Make a small change to config to allow a custom Elasticsearch port.

[ahalterman]

Also:

• update documentation, including to talk about version
• switch some Caerus URLs to OEDA (see Switch dependencies to OEDA infrastructure #6)