Migrating away from acid-state

Hi there,

I've got some open source budget at work, and would like to put it towards `hackage-server`. In particular, my thoughts were to replace the usage of `acid-state` with a postgres database. By my reading, this would allow us to:

1. use traditional database backup techniques
2. remove a huge amount of code around managing tarball backups
3. dramatically lower hackage-server's memory footprint
4. probably solve #1276
5. remove the custom search engine implementation
6. allow for migrating data separately from shipping new binaries, which in turn will likely improve uptime

All of this is likely to help #1467 as well.

I just wanted to ensure there is an appetite for this work before I invest too much time. Happy to setup a call and discuss the finer details as well.