fix bug 965590 - unify socorro to a single virtualenv

@peterbe ah makes sense, bit of overlap with bug 965590 I guess?

Any reason not to take what I've done now and consolidate ```vendor``` later? This current PR doesn't make us any worse, and arguably makes us safer now (because we'll be using ```peep```). We also save some time+space because we were double-installing things like ```psycopg2```