Sparrow database upgrade process

[davenquinn]

sparrow db upgrade should create schema extensions specified in SPARROW_INIT_SQL. Otherwise, there is the possibility that lab updates to the schema can create non-deterministic upgrade conditions.

We should also figure out a more robust way to test schema migrations. Maybe with a separate testing suite specifically for dry runs of this?

[davenquinn]

We now have a good schema migration testing suite, which runs on sparrow test