Removing TODOs from storage.key.
Removing TODO from tox file.

Also removing some trailing spaces (thanks emacs config).
Remove vague TODO from exceptions.
Remove TODO from storage.iterator.
Remove TODO from storage.__init__.
Remove TODO from storage.acl.
Remove TODO from datastore.helpers.
Remove TODO from datastore.key.
Remove TODO from storage.bucket.
Remove TODO from storage.connection.
Remove TODO from datastore.connection.
Remove TODO from datastore.query.
Remove TODO from datastore.entity.
Merge pull request #175 from dhermes/move-todos-to-issue-tracker

Move todos to issue tracker