Teach setup-dependencies.sh two install modes

Privileged mode installs python package dependencies systems wide.
Unprevileged mode installs them in the virtualenv.
Commandline args required: -u|-p
Now uses pip 1.5 so that we don't allow arbitrary code execution.
gpg signing key for pip updated to Donald Stufft's key 3372DCFA
Merge branch 'master' of github.com:TheTorProject/ooni-probe into setup-deps
Make the ipaddr dependency less strict.
Fix the requirements.txt to download the https hosted versions.