flowFactoryProvider configuration comment added regarding chunkSize.
Need to deal with missing data structure for required data such as:
ELFIN/PARTENAIRE/FOURNISSEUR not to block user from updating data.
Using controller function to trigger upload elegantly solves headaches 
to reliably set flow.opts.query.
Configure flow not to test chunks setting testChunks : false.
Using controller function flowUpload($flow) to trigger upload elegantly
solves headaches to reliably set flow.opts.query.
Additional code clean up.