Metadata fields

[minamouse]

Currently, it seems like all the metadata fields are hard-coded into indexed_piece and aggregated_pieces. This makes it difficult to add new fields, especially if we want to be able to easily parse them from somewhere else (like the elvis database).
Maybe there can be a better way of having the metadata options more easily expandable?

[alexandermorgan]

This is a great idea but it unfortunately won't make it into VIS 3.0. This could be a good project for later in the fall.