Include bridge country codes in sanitized bridge descriptors

Before May 2010, we resolved bridge IP addresses to country codes in the sanitizing process and appended them to the nickname, e.g., UnnamedDE. This was possible, because we sanitized descriptors in batches which was a semi-automatic process.

When we switched to sanitizing descriptors automatically, we took country codes out, because the code was too complex and broke all the time. The difficulties were that descriptors can arrive in any order (while we still need to come up with the same set of sanitized descriptors) and that we need to update the GeoIP database periodically. That's not impossible to solve, but also not easy to get right.

We should find a way to make this work, maybe by relaxing the requirement to update the GeoIP database at all. The old code that we took out in May 2010 is here.