Add PLUMBER2 option for CLM_USRDAT_NAME for datm similar to handling of NEON

[ekluzek]

trafficstars

For NEON we have CLM_USRDAT_NAME that can equal NEON or NEON.PRISM. We need something similar for another set of tower sites called PLUMBER2.

This will mean modifying things under datm/cime_config:

buildnml stream_cdeps.py (in ../../cime_confg)? namelist_definition_datm.xml streams_definiton.xml