Programmatically generate solr response for the niec element, complete boilerplate for nested setter/getter access.
Elementary solrization tests and basic setter/getter sanity checking.
If '2014' is a valid entry for the publicationDate format, this field isn't storable as a Solr date field.  Since I assume all of the date fields in the NIEC extension are as loosely constrained, I've moved them over to string storage for the time being.
Add a NIEC fixture file for potential future testing - insert NIEC Solr Hash generation into the mods #to_solr method.