Support username change

[binkoni]

Added username change support

[binkoni]

Hmm.. no plan to support this?

[leafo]

sorry, I must have missed this pull request. Looking over it

[leafo]

Changing usernames can break URLs to manifests & packages.

• Minimally we should have a big warning about changing your username, explaining why it might not be a good idea
• We can set up an automatic redirect for the old username to the new username (both for profile pages, and manifest/package urls)
  • A new model would need to be created, UserRedirects or something similar
• On other sites where I've implemented username changing, I tend to keep the old username locked. This means preventing an account using a previously used username to stop hijacking any old URLs. I think this is especially important for a package manager.

[binkoni]

@leafo Thanks for the response. Since it seems to take some time, I'll implement what you said when I have some time.