Spgemm hash promotion

[ndellingwood]

As worked on by @mndevec and submitted in PR's #134 and #139.
Issue added for documentation and CHANGELOG tracking.

Quoting from #134:

Updating SpGEMM methods. These will be in the next KokkosKernels promotion to Trilinos.

1- New parameter selection on GPUs. This adjust the shared memory size, block size, vectorsize.
2- New meta-algorithm called SPGEMM_KK. This is the default algorithm from now on. ---> SPGEMM_KK_MEMORY = KKMEM is outdated.
It chooses the best algorithm to run based on the input structure.
For example, it may choose dense accumulators or sparse on CPUs.
On GPUs, it adjusts the old KKMEM parameters as above, or it may choose to run a block-based algorithm rather than a warp-based one (KKMEM).
3- Minor updates: changing the test driver calls. It now requires "--" before parameter name that was missing previously.

4- The new parameters name is SPGEMM_KK. In the xml file, any of the below will run this default algorithm. Please use the ones below after the new kokkoskernels promotion:

• "SPGEMM_DEFAULT", "SPGEMM_KK", "SPGEMM_KK_MEMSPEED"