Addressing feedback in review for main pylint changes.

- Reverting refactoring changes of code re-use between
  storage.Key and storage.Bucket. These will be committed
  in a separate PR.
- Turning off the `no-self-use` warning for test code and
  reverting all the copious `@staticmethod` decorations in
  test and demo code.
- Removing a refactroing note about storage.bucket.Bucket.from_dict
  from the code.
- Fixing indent on a module attribute docstring in storage.key.Key
- Updating note in pylintrc files to make the intent more
  clear.