Bug 836106: Ensure basket data is in sync with ET.

Fix issue with 500 errors on ET errors.
Bug 843103: Upgrade to latest basket-lib, which has upgraded Django.
Merge pull request #19 from pmclanahan/bug-843103-upgrade-django

Bug 843103: Upgrade to latest basket-lib, which has upgraded Django.
Merge pull request #16 from dpoirier/update-readme

Bring README.rst up to date
Add ALLOWED_HOSTS setting.
Add hit counting and view timing with statsd.
Merge pull request #20 from pmclanahan/add-statsd

Add hit counting and view timing with statsd.
Merge pull request #15 from pmclanahan/keep-users-in-sync

Bug 836106: Ensure basket data is in sync with ET.
Bug 806327: Enable async ET operations.
Merge pull request #21 from pmclanahan/bug-806327-async-subscribe

Bug 806327: Enable async ET operations.
Update admin to include celery.
Store newsletter data in basket

- Add database models to store information about newsletters, e.g. name,
  description, whether active, supported languages, etc.
- Add an API call to fetch that information.

Branch: (no branch)
Refs #841426: Respond to PR comments

- remove pointless test
- require GET for newsletter API