=== Value proposition:
Users report being confused when they see the //Upload to Commons// button as disabled. It is not immediately clear to them that they need to login before they can upload.
=== Proposed solution:
Two possible options (in order of preference). Let's do whichever is easier:
1. Keep the //Upload to Commons// button always enabled and if user is not logged in, the button takes them through login process and uploads the file at the end, with the user landing back on the translations page with the green banner about successful upload.
2. Add a statement indicating that a user needs to be logged in underneath the //Upload to Commons// button if that button is disabled. This could look something like:
(Note that the "Login" here would link to the Oauth login just like the one on top does)