Wrapper updates for Reproducible Sums

[Katetc]

Bill L has fixed CISM such that it can give identical (B4B) answers with changing processor counts! We will need to bring this code into CESM. Here are the important to-dos along the way.

• Review PR in CISM
• Set up Wrapper branch to support the change. Note from the PR:

To generate reproducible sums, the user simply sets reproducible_sums = .true. in the config file. The default setting is false.

• New test(s) for repro sums
• Document, Merge and tag CISM branch
• Test and tag wrapper branch
• Add to CESM DB