Update the vendor submodule; fix issues with newer pip

The (old) version of playdoh-lib we're using right now depends on an old version of funfactory that requires a version of `py-bcrypt` that can't be installed using newer versions of pip (for reasons unknown to me). We shouldn't be using playdoh-lib in the first place, but that's a topic for a future discussion.

Changes:
  - Update the vendor submodule (playdoh-lib) to a revision **after** playdoh-lib changed the funfactory dependency but **before** it switched from Django 1.4 to 1.5
  - Update django-reversion to a version that newer pip can install
  - Fix issues caused by a Django debug toolbar update
  - Fix issues caused by a Celery update

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- [ ] Tests pass
- [x] South migration works
- [x] Maintain migration works
- [ ] Web interface works
- [ ] Django debug toolbar works
- [ ] CSRF protection works