Fix Bug 914193: Upgrade to latest basket-lib.

* Django 1.5.3.
Merge pull request #81 from pmclanahan/upgrade-django-bug-914193

Fix Bug 914193: Upgrade to latest basket-lib.
Bug 907330 - confirm notice handle short form of language

If user has selected 'pt', and our newsletters only list 'pt-BR' as a
supported language, that should work.