Set the GeoIP cookie client-side even if request failed

To prevent honest-to-goodness IPv6 users from having to try and fail to
resolve the address of our IPv4-only honey trap on every single request,
cache the result as a cookie.

Change-Id: I1295052b5e409274524f1b78497e09a8233e2c12
Merge "Set the GeoIP cookie client-side even if request failed"