making significant changes to simplify the exerciser benchmark, and to add documentation. You should look a few commits back to see some of the topology-aware and early-ccio-specific cunctionality that has been stripped out for simplicity

Correcting serious issue with BW calculations -- Needed to change the command-line args to read in the number of elements in each dimension of the minimum-size dataset (NOT the number of bytes)

Adding more options to the exerciser (including new options to add custom stride distances, memory hogging, performance counting, and self validation). There is also a new Excerciser/Cray/ directory with an example script and corresponding README.md file (to help Cray get started with this testing code). Note that the memory hoggin option and custom stride options (--memuse and --stride) are somewhat limited and experimental). In this version of the code, the hdf5 datasets must be <=4 dimensions (this is easy to change in the future, but was more convenient for now).

There seems to be an issue with craympi 7.5.5 hanging (this was a workaround
for slow RMA performance at high (> 64) ppn) so just stick with current craympi
for now.

Updates to README and new submit.sh file.

Initial commit just to build it.