DB may be corrupted by concurrently running server

[d1m0]

Currently our database is a single sqlite file per experiment. As you can have multiple servers running at the same time in an experiment (when you pulished multiple hits at the same time) you can have concurrent accesses to the database. This can lead to corruption. Options include:

1. For now only run 1 hit at a time for experiment
2. Use a file lock
3. Use an actual db server