Implement a filesystem database backend

[Misterblue]

For simple metaverse-server setup, implement a storage backend that does not require MongoDB but rather uses just the filesystem.
Stretch goal would be an object storage backend (S3, ...) but real requirement is for simple, one-thing-to-install-and-build server solution.

[Misterblue]

One solution for this might be using run-time installable MongoDB that has been developed for testing. Several projects exist for NodeJS that install and run MongoDB on demand. This was developed for test suites but the mechanism could be used for an easy MongoDB that is persisted in the filesystem.

Some projects I found are:
https://github.com/mongodb-js/mongodb-prebuilt
https://github.com/jeresig/mongo-in-memory
https://github.com/nodkz/mongodb-memory-server