Provide option to bypass the public CRAN_mirrors URLs in the TERR Tools package management tab

Provide an option for a Spotfire Administrator to point the Spotfire Analyst desktop client's "Tools > TERR Tools > Package Management" dialog tab to the URL of a custom R package repository.

This option would bypass the dialog's "CRAN package repository" drop-down list of CRAN mirrors that is populated by querying the following URLs:

https://cran.r-project.org/CRAN_mirrors.csv
http://cran.r-project.org/CRAN_mirrors.csv

Why?

This would provide the following capabilities:

• point-and-click access to R packages without whitelisting the public CRAN_Mirrors URLs in corporate firewalls

• point-and-click access to a limited suite of approved R packages, and no others