Rgeo-proj4 & postgis config for CircleCi 2.0

I noticed that I’m not the only user that has run into this issue

https://discuss.circleci.com/t/libgeos-not-recognized-in-circleci-2-0-environment/22451

I’m just wondering what the best way to alter my config file to ensure the proj4 library needed by the rgeos is installed.