Upgrade to Django 1.5.9.
Merge pull request #102 from pmclanahan/upgrade-django

Upgrade to Django 1.5.9.
Bug 1064977: Add ability to use ET sandbox environment.
Merge pull request #103 from pmclanahan/add-et-sandbox-capability-1064977

Bug 1064977: Add ability to use ET sandbox environment.
Bug 1051806: Add /fxa-register endpoint.
Bug 1054316: Trigger welcome email for fxa registeration.