Handle RAW images formats

[babolivier]

As requested by an user, it would be interesting to support the major RAW image formats, like DNG (Adobe), ARW (Sony), NEF (Nikon), CRW/CR2 (Canon)... List of main RAW image formats can be found here (FR).

This would need a processing tool located in the DataSystem (if we take Cozy's current architecture) to convert these RAW images in JPEG to make them readable by a browser. A small list of FOS tools to process RAW images can be found here.