fix bug 965590 - unify socorro to a single virtualenv

Why does this need to be here? It's already in webapp-django/vendor (or webapp-django/vendor-local)
I think I've thus filed a dupe https://bugzilla.mozilla.org/show_bug.cgi?id=980351 but nevertheless we can't change to requirements.txt until we've removed it from the vendor (or vendor-local) directories. Otherwise we'll end up with potential confusion since the `./manage.py ` script makes sure the vendor libs come first and you might think "But?! I ran pip install but still it's using so and so version"