Setup lbann as library

[bvanessen]

To integrate with the CANDLE SwifT framework we need to be able take an MPI comm world so that we can be called under the SwifT MPI ecosystem.

[ndryden]

lbann_comm already has support for this in its constructor. Is that sufficient?

[bvanessen]

We need to test it in the CANDLE hyperparameter tool.

[ndryden]

Can you point me to it so I can test it? We already have an lbann library built, but the lbann executable (which handles loading prototexts, etc.) is separate.

[bvanessen]

Yes, I will figure out how to get us going with it.