Move to relational vcf storage and backend queries

This is The Great Migration. 

This PR introduces a schema for and code around loading VCFs into a PostgreSQL database, as well as querying those records via a JSON RESTful API. 

Much work needs to be done to fully integrate this and patch up the code touched by the change (hint: most of it). 

1. Charts and the Karyogram on the examine page.
2. Clean up SQL construction
    1. Remove or update models.py
    2. handle possible injection issues (use SQLAlchemy more here?)
3. Clean up views.py
4. Improve validations.py & associated field names. 
5. Explore: Serialize records and send them to client after initial load. 
6. Performance optimizations.
7. Robust workers.
8. Fix concordance worker & visualization (need a new table in the DB).
9. Fix/remove scorer worker.
10. TESTS!
11. Variant sorting tabs need to be fixed.

And probably some more. Will be adding these as issues.
Request as in "asking for something", nothing specific to network behavior. I could change it to RequestPage instead, though then the handler (in ExaminePage) would be "handleRequestPage" instead of "handlePageRequest", but I can change that. 

The action is not asking for the table to be extended or for the visible range to be extended; it's asking for more records that the requesting component can do with whatever it pleases; in this case, it will extend the table: it's not requesting that the RecordStore extend the table.