Create file system before account registration

[bgins]

Summary

Problem

Users need to create an account to access the file system.

Impact

It challenging for developers to create apps that use local-only file systems.

Solution

Always create a file system, even before the user registers an account. An app can use the file system in local-only mode before an account is created, which would mean the file system is not published. When a user creates an account, start publishing the file system.

Note that there is some overlap here with #475, but the convenience method for temporary file systems may be useful for creating multiple file systems.

[icidasset]

Implemented on next branch.