Site wide default settings for the colors on metrics

Originally from ticket #3224.

It would be nice to be able to set default colors for new metrics at the site level. This way we would not have to set colors for metrics that used the site default colors for below minimum, minimum, meets, and exceeds. 

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Submitted from: https://col.connectionsonline.net/4/6fd1e75d-a5d3-4d75-8488-0593990164d6