Parse uploaded files for search index keys

Working for GraphSON, GraphML, and Faunus's version of GraphSon (still figuring out how to parse GML in js).
Basic workflow is:
- user selects file in UI
- js parses based on filetype and either emits parse error or triggers popup modal
- popup modal enables user to checkbox-select search indices
- server takes list of requested indices and creates each if it doesn't already exist and if it isn't a reserved index field