Greatly improved first upload

[calpaterson]

Brief overview

AS A user uploading my first table

I WANT the error handling to be more robust

SO THAT my mildly odd csv has a better chance of eventually getting in

Additional details

Some constraints:

1. Users who create an account at the same time as uploading their first time should not have their user creation rolled back if it fails
2. Errors creating a table should be returned to the user
3. If we really can't get it, suggest then to create a new blank table and then bulk upload to it
   • for extra marks, prefill this form