Add new field for community classification framework
2) we need a framework for communities wherein we are placing a plot. This was
thought originally to go into commClass and we'd mandate that only communities
adhering to this framework could be linked from a classification event.
However, we now believe it would be better to put this into commInterpretation,
because we may need to classify to a different framework at a higher level (CVS
higher levels) when CEGLs do not exist for a plot's community. Field:
commInterpretation.cust_cvs_framework_id - reference which describes the
classification system used, e.g. Braun-Blanquet, Forest Service Cover Types,
US-NVC, or an idiosyncratic system.