MPI Calculate Pair Vector Average Update

This minor update provides a new utility function called MPI_calculatePairVectorAvg for calculating the average of distribution data coming from different processors.

For a complete listing of the new changes, see the Changelog

This release was developed under the financial assistance award 70NANB14H012 from U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design (CHiMaD).