Build benchmark low-level script with drill

https://github.com/fcsonline/drill

• Start by writing manually a scenario that is able to test multiple localhost servers
• If needed, generate scenarions through python code

A simple scenario would be:

• download all info.json from all known images
• generate a 404 on an invalid image path
• download full image without resize
• download full image with a resize
• download some sub parts of all images

Depends on #4 (closed)