Migrate some functions from librairy/utils to librairy/models (previews
generations, metadatas loading, previews and file deletion)
End of migration from pillow to wand. Previews generation functions are
now in librairy/models, and it's slow, need to fix it.
End of migration from pillow to wand. Possible to earn a bit more perf
adding a "clone" method in ThumbnailFactory.
Bit of cleaning.
Update install instructions, add a requirements.txt to install pip
dependancies automatically.