Create a "Docker Free" Version of dGen

[michaelavs]

Issue overview

Users have asked for a version of dGen without the Docker dependency due to licensing issues for their organization. The dGen model uses Docker primarily for the "mdillon/postgis" image that automatically enabled Postgis in the PostgreSQL database. As of PostgreSQL version 9, Postgis is automatically enabled. If it is not, it is easy enough to enable this extension through psql commands in the terminal/command line or in the pgAdmin app. We have also discovered the "mdillon/postgis" image is depreciated/no longer maintained.

The "Docker Free" version can be complimentary/an extension to the current dGen model as some users may find using Docker to be an easier/faster option than downloading and setting up PostgreSQL on their computers. Preliminary instructions have been developed for the Docker Free version of dGen and can replace the current homepage instructions while linking to the Docker/Packer instructions (in development by D. Whiteside in PR 54).

[pkrulz]

Additionally when working on this please change the default behaviour to not use dgen_db in the sql files.
That way multiple databases with different names can exist and one can easily choose whichever to choose by simply changing the json file