Give the whole dev team access to the PrivateStorageio staging infrastructure

As a {product,project} manager I want to give the whole development team access to the staging infrastructure, so that everyone can look up and try out things themselves and never is blocked on not having that access.

This is done by adding a public SSH key to this file. Awaiting your merge requests :) Or, if you'd rather do that, you can also just send @florian your SSH public key.