Universe field in variablemetadata table

[lubitchv]

Recently we needed to import datasets with variable file level metadata and we discovered these files have variable file level metadata that has field "universe" for a variable that is much bigger than 255 character. Therefore update of var metadata for these files failed. Presently all the string fields in variablemetadata table have type text except the "universe". It would be helpful for our import to change universe field from 255 characters to text type as the rest of the fields in the table.