Remove need for permission to upload sources

[jgonggrijp]

When uploading sources first became possible, it was available to all registered users. Soon after, @alexhebing added a restriction to allow this only to admins. I could not find any documented rationale for this restriction, but it provides some protection against spam, so that might have been it. In #262, we discussed that uploading sources should rather be a privilege that can be independent from being an admin. This is how we ended up in the current situation. More historical references can be found through #175.

Post-development, keeping this restriction in place is undesirable for two reasons: (1) since the beginning, the intent of the project has been to be open to the general public (compare #180, #418) and (2) maintaining the restriction implies that someone has to be available to give the privilege to new users.

Removing the restriction is fast and straightforward, since it only requires making code that is conditional on the privilege unconditional instead, or conditional on being authenticated. However, we should hold off on this until #478 is in place, in order to not open the floodgates for spambots. It will also be most practical to wait until after #444/#500, and the upload form should explicitly advice people not to upload overly long sources (#391).

[JosedeKruif]

Also, the WP consortium members (those that are still around) decide if and when the application is open to the general public. Keeping the restriction might be undesirable, but it is their decision to make.

[jgonggrijp]

Right. Shaf and Brigitte have both confirmed that they want the restriction removed.