Add option to rename metadata columns

[shaeHansen]

trafficstars

Requesting the option to rename metadata columns. Currently, if a column is renamed and new metadata uploaded, the new column is added but the old column remains and has to be deleted. If multiple columns are renamed, each old column has to be deleted one by one.

Requesting a new text entry that accepts: old_column_name1: new_column_name1, old_column_name2: new_column_name2, ... old_column_nameN: new_column_nameN