Is GCS backend functional?

[RaJiska]

Hi,

I am trying to setup PrivateBin with a GCS backend. When I look into the code and fix the issue, another one appears, and then after than another one.

When I compare the metadata between a file generated in GCS and a file in FileSystem, GCS seem to miss a lot of it, and actually don't even have the key names consistent with Filesystem (e.g: metadata instead of meta).

Has GCS been tested and is it a feature I misconfigured or does it still need some work?

EDIT:
Made a PR #988 to make it work.