Dynamic NuGet Package Server Setting

[charleslbryant]

We have two build servers. One private that is behind a firewall without internet access. Another one is public with internet access. When we build on the private we need to point to an internal NuGet server and when building on the public we need to use the public NuGet server because access is restricted to the internal server.

We need to update the build so that it will dynamically set the NuGet server depending on a config file that has the NuGet server path set depending on the build server.