Currently, when a PPA is disabled, it continues to be listed in the owner's page as an enabled one and can be traversed in the UI. The only difference is that we render a warning message in the PPA page itself stating it's disabled.
That doesn't satisfy cases like:
* A PPA was created with a non-ideal name and the user request it to vanish from the UI
* A PPA contains packages that violates the PPA ToS.
For covering those cases, marking a PPA as 'disable' should result in:
1. PPA is only listed in the owner's profile page if the requester is an upload or admin and it should be clearly styled as so (crossed-link or something similar)
2. Only uploaders and admins should be able to traverse to a disabled PPA (the warning should continue to be rendered)
3. Owners should not be able to create a PPA with the same name than a disabled PPA.
4. Dependencies on a disabled PPA should be ignored as listed appropriately in their context.
5. Package cache indexes for disabled PPAs should be removed in the next update-pkgcache run.
Points 1, 2 and 3 addressed in r9015 (devel).