Curating institution .janno column

[nevrome]

I added a .janno column as discussed in #82. The anonymous reviewer wrote:

Curating_Institution Column?

I think it would be useful to have a column naming the institution that curates the bones (or at least the one that curated them at the time they were sampled) for reasons of openness and replicability but also in terms of acknowledging the input of those institutions.

I think the name Custodian_Institution is a good fit.