+me/+packages should present different sections for sponsored uploads

[Celso Providelo]

In the current UI the user is not able to track sponsored uploads appropriately.
The infrastructure required to isolate sponsored uploads is already in place:

  1. PackageUpload.signing_key.owner != SourcePackageRelease.creator -> identify sponsored uploads
  2. when the user in question is the signer, the upload should be listed as 'Mentored Uploads'
  3. when the user in question is the creator, the upload should be listed as 'Sponsored Uploads'

or vice-versa on 2 & 3, I'm not sure which one is clearer.

When viewing the packages page of someone other than the logged in user, some indication of which uploaded packages on the page were sponsored by the logged in user (such as an icon) would also be useful, for example, when one developer is trying to see which packages they sponsored for a candidate-for-upload-rights to write their recommendation.

[Julian Edwards (julian-edwards)]

Add this information to +queue and +me/+packages

[Dimitri John Ledkov (xnox)]

Currently this is used:
http://ubuntu-dev.alioth.debian.org/cgi-bin/ubuntu-sponsorships.cgi

It is helpful when applying for Ubuntu Developer status and gathering comments.