Support CSV file upload

[jackparmer]

This blog post review of Falcon recommended CSV file upload so Falcon can be more on-par with something like Tableau Public. Seems like a useful idea and easy to add.

@nicolaskruchten recommends http://papaparse.com/

[nicolaskruchten]

Nice! Does the PR that closed this actually allow a user with local CSV to query it or must it be uploaded to a URL?

[n-riesco]

@nicolaskruchten No, just URLs. I've opened #383 to discuss how to implement uploading user's CSV files.