mapvizieR should attempt to discern which norms were used when a CDF is read in

[almartin82]

probably by looking up some of the norms against a norms table.
then we could store that in some sort of metadata slot on the mapvizieR object.

not sure exactly how we would use that right now - and because we have the consistent percentile practice, we don't need to worry about the % making growth being wrong - but since this is variable on the CDF generation, we should try to figure out what is going on at import.

[chrishaid]

The new 2015 CDF includes a field that tells you which norms were used.