Store runs somewhere else

[glacials]

We're storing run files as strings in a file column in the runs table. This is messy, because some run files are on the order of 10 Mb in size, so we have to avoid selecting this column when we don't need it to get anywhere near decent performance.

I don't want to get rid of storing the files, because they hold a lot of data that we don't yet duplicate (like history) and we should be able to serve these files in their complete forms. But moving lists of splits themselves into the database, so that we never need to access or parse files unless we're serving them directly, may be a prerequisite to moving files to an external service like AWS without introducing more complexity for file retrieval.

[glacials]

This should be fixed in a way that also fixes #13.