Export Queries that don't have judgements

[epugh]

Is your feature request related to a problem? Please describe.
Today, via the Basic export format, we only export queries that also have documents and ratings:

query	docid	rating
Example	1	4

If the query Example was completely unrated, or if it doesn't match any documents in our corpus, then it won't export.

Describe the solution you'd like
I'd like to be able to export all documents in the Basic usecase, as I might be exporting queries to an third party system for rating. They might not have judgements, or they may not match docs due to terrible search, but I still want to have those queries judged:

query	docid	rating
Example	1	4
Unrated Query	5
No match Query

Describe alternatives you've considered
This could be just the default way that Basic export works... Or, do we make the current behavior the default, and add a checkbox for "Include unrated queries" that would bring in the Unrated Query and No match Query examples?

Additional context
This feature is only useful if you are rating documents outside of Quepid, but creating the queries in Quepid. However, as part of a ecosystem of products, we want to facilitate that workflow!

[epugh]

In poking around, it turns out that if you want to have the docs related to a query, you must SNAPSHOT the case.

[epugh]

Fixed in #191.