Revert "updating number of receives to post in distributor"

This reverts commit 9314736d8b57d0d0722df8811936e59c4fc979e6.
Revert "changing MPI_Reduce to MPI_Ireduce in Distributor"

This reverts commit 7a21ca8a13f7ec5dc1e3a0e3a5e12e5a4655bfcd.