geoBoundaries 4.0 - Feature Freeze

[DanRunfola]

Just a note for the record that I have frozen our issues list for gb 4.0 today (8/04). Any further issues will be added into the 5.0 queue.

Of note, the versioning setup will allow us to publish updates in near-real-time, so this freeze is really only relevant for individuals using the tagged 4.0 releases.

All updates to 4.0 will be available here:
https://github.com/wmgeolab/geoBoundaries/milestone/3

Ultimately, 4.0 will have approximately 500 improvements over 3.0. More on that with the formal release.