The Craedl SDK now supports Craedl's newly introduced file version control feature.
**Changes:**
* `Directory.create_file(...)` is unchanged in the SDK and automatically adds a new version of the file if the file exists and has changed.
* `File.download(...)` now takes an optional `version_index`, to allow you to choose to download a particular version. The index comes from the chronological ordering listed in the `File.versions` attribute. Leaving `version_index` unspecified downloads the version that is currently active.