This is currently failing, to replicate the bug reported in #67.
Will add a fix for this next.

Previously we assumed that Loc_name would always be provided, given
that we ask for it in the requested field list. However, when using
the magicKey, the Loc_name is not provided, causing geocoding to
fail. By making it optional, we allow those geocoding requests to
succeed.

Also, add a WARNING to the log when there's a missing key, instead
of just silently passing, for better observability.

This new value is used for many responses now, need to include it
for the tests to pass.

Disable Google test if credentials are missing.

Not sure what was wrong with the Philadelphia address for Census
purposes, but switching to an Alexandria address fixes that.