* Creating a spack package for LLNL's LBANN (Livermore Big
Artificial Neural Network) training toolkit.
* Recipe for building LBANN toolkit. Contains limited feature set and
is optimized for building with GNU gcc and OpenBLAS.
* Removed unnecessary dependencies based on reviewers feedback.
* Added support for the int64 data type in the Elemental library. This
is required for supporting indices for large matrices.
* Added a variant to force a sequential weight matrix initialization.
This is slow, but provides an initialization that is independent of
model parallelism.
* Added a guard to prevent building Elemental with the Intel compiler
for versions that have known bugs.
