fix setup-dependencies.sh

    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