Add an option of local file system access for image projects

[EugeneSel]

Is your feature request related to a problem? Please describe.
It is currently impossible to use Annotto for images without access to S3.

Describe the solution you'd like
Add an option for the image projects, allowing to fetch files from local storage.
E.g. create a docker volume with images to use and item.data.url would contain a path to an image within this volume.