Snap license metadata

We discussed this today in the call, and we now understand each other.

The suggestion from @chipaca is that instead of requiring manual fiddling with an editable label in the store, it’s much simpler to always take the license from the stable channel. That’s a good idea and simpler in all angles. The only bit I’d amend is that we should pick the license from the most stable channel, not just stable itself, because we need to show something if there’s no snap in stable.

So, the next steps are:

  1. Implement the described logic in the store
  2. Support custom licenses
  3. Change snapcraft to warn about missing licenses
  4. Change the store to reject new snaps without licenses

Step 4 needs to wait some grace period until everybody had a chance to update their snaps.