[bug 785856] Add billiard to vendor.
[bug 785856] Upgrade celery to v3.0.24.

* Updates celery to v3.0.24
* Updates django-celery to v3.0.23 (there is no v3.0.24 for django-celery)
* Adds amqp v1.4.2 replacing amqplib v1.0.2
* Small code changes to match the new API for celery
* Migration that adds missing tables for celery
Use https:// instead of git:// in .gitmodules
Fix pip call in travis/install.sh

Pass parameters: --allow-external PIL --allow-unverified PIL
Remove .pyc files in vendor during deploy.
Cleanup crontab.

* Removed commented out call
* Changed cleanup and get_customercare_stats to daily (from hourly - WTF?!)
Add contributor counts script
[bug 967045] Only show register form in AAQ or Get Involved.
Update redis configs for v2.6.x
Update travis scripts to use redis v2.6.9.
Fix l10n fail
[bug 963088] Fix deprecation warnings in manage.py
[bug 958285] Bust images cache when answers are edited.
[bug 952770] Reindex on username change.
[bug 972832] Removed usage of /wafflejs
Fix issues with SUMOMO data migration.

* Unmark redirects as localizable.
* Remove duplicate {} that were made in the migration script.
[bug 966738] Stop shrinking the font.
[bug 889166] Spritify uploaded icons