Delete records from Exact Target

* Add a method to delete a subscriber's record from one of our Exact
  Target data extensions, given the token.
* Manually tested with my own data extensions, verified that it deletes
  the desired record and no others.
Bug 853990 Fix suds cache usage

We made a change to use our own cache with Suds, but it turns out that
Suds uses named type checking to validate the cache instead of duck
typing, so we need to inherit from Suds's cache even though we don't
use anything from it.
Merge pull request #77 from dpoirier/bug-853990-fix-suds-cache

Bug 853990 Fix suds cache usage
Merge pull request #76 from dpoirier/delete-et-record

Delete records from Exact Target
Bug 875369 - Better logging of basket task failures

When a basket task fails, log the full arguments, in case we need to
try to run it again after the problem is fixed.

Also try to log fewer messages, and make the ones we log more
similar to give Sentry a better change to aggregate the related
ones.
Merge pull request #74 from dpoirier/bug-875369-basket-task-failure-logging

Bug 875369 - Better logging of basket task failures
Bug 901541 - Newsletter recovery email

Add API that given an email address, sends an email to that address
with a link to allow that user to manage their subscriptions.

If email is not known or not subscribed to anything, returns 404.
Merge pull request #75 from dpoirier/bug-901541-newsletter-recovery-page

Bug 901541 - Newsletter recovery email
Add coveralls.io support.
Merge pull request #78 from pmclanahan/add-coveralls

Add coveralls.io support.
Omit test files from coverage report.
Update vendor to upgrade to Django 1.5.2.
Bug 875369 - Log failed Basket tasks

When a basket task is unable to complete (after exhausting its allowed
retries), log the task name, parameters, and whatever exception made
it fail into a database table where we can look at it later.
Merge pull request #79 from dpoirier/bug-875369-log-failed-tasks

Bug 875369 - Log failed Basket tasks
Bug 907330 - standardize confirmation message IDs
Bug 907330 - don't call newsletter_languages twice, fix import continuation line
Merge pull request #80 from dpoirier/bug-907330-standard-confirmation-messages

Bug 907330 - standardize confirmation message IDs
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.