mbonino

I believe the issue is cause by [this assignement](https://github.com/yeti-platform/yeti/blob/fcd3ee3d3d064df772d0392c20c22aad2bc4c8e6/core/web/webapp.py#L21). I changed it to: `webapp.secret_key = b'A_fixed_pregenerated_random_value'` and I don't have login issues anymore.