Example Dropbox Setup

[brendoncarroll]

Create an example showing how to setup a synchronized volume for root directory. This is probably the most common use case.

The objects would be structured like this:

Volume{ RootCell } -> Volume{ CryptoCell{ HTTPCell } } -> Dir

Every device has it's own root volume, which immediately contains a shared networked volume. The secretbox cell is probably ready for use because its so simple, but it requires transporting the key to multiple devices.