libpostal requires data files which should be fetched before use.

Fetching data files requires 776M of free space, and the extracted data
takes 1.8G.

The user fetching data must be part of the _libpostal group:

# usermod -G _libpostal <username>

The data files can then be fetched as follows:

$ cd /var/db/libpostal &&
for f in language_classifier libpostal_data parser; do
  ftp https://github.com/openvenues/libpostal/releases/download/v1.0.0/$f.tar.gz
  tar xfz $f.tar.gz
done;
