[master] Fix database update

[davide-scola]

This set of changes fixes several long-standing issues; here is a list of all the most notable changes:

• geoip-lite dependency has been updated to the latest version available: this is required as updatedb.js script was from version v1.4.10 (see Staging: update for maxmind URL changes and 302 redirects #24), but dependency within the package.json file was 1.4.6. Due to a change in how unassigned blocks are handled starting with version 1.4.8 (see Incorrect geolocation for non-geolocated IPs geoip-lite/node-geoip#254), this error may have been experienced:

:~$ grenache-request -s '1.1.1.1' 'rest:util:net' 'getIpGeo'
ERR_API_ACTION: The value of "offset" is out of range. It must be >= 0 and <= 11664748. Received 377_957_121_965
:~$ 

• maxmind dependency has been updated to the latest version available; this fix an issue with the file watcher in older versions (see Unhandled rejection when watching for updates runk/node-maxmind#238). However, openSync is no longer available, hence a slight worker refactoring was needed
• updatedb.js script is now the same as the latest version available, published by the geoip-lite project, with the minimum set of changes needed to use premium databases; this makes it easier to keep track of changes (linting is disabled for this file)
• several fixes to the update-asn-db.sh script:
  • maxmind license key is now taken from a file if it's not supplied via an environment variable
  • destination directory is automatically created if it does not exist
  • conditional download has been restored (see [master] Update the ASN database only if it is newer than the local copy #7); database is downloaded only if it is newer than local version
  • database is copied to its final destination from a temporary location, as atomic replacement does not seem to trigger the file watcher
• several fixes to the update-geo-db.sh script:
  • maxmind license key is now taken from a file if it's not supplied via an environment variable
  • destination directory is automatically created if it does not exist
  • databases are copied to their final destination from a temporary location for integrity, as update process takes time to complete