go get now always updates and all commands are run in parallel

Usage:

    fab -i ~/.ssh/amazon/ec2_cloud_east.pem -H
    ec2-user@184.73.44.73,ec2-user@54.87.32.160
    start_server:"10.126.38.49 10.223.21.77 10.223.21.78"

    fab -i ~/.ssh/amazon/ec2_cloud_east.pem -H
    ec2-user@184.73.44.73,ec2-user@54.87.32.160
    setup