allow downloading and running scripts from the web

[ssbarnea]

Another common use case is where you want to run a script that you download from an url.

Example usage:

rmux -w https://bootstrap.pypa.io/get-pip.py --help

Desired behaviour on remote machine(s):

curl https://bootstrap.pypa.io/get-pip.py > get-pip.py 
chmod +x ./get-pip.py 
rmux ./get-pip.py --help

Practical use: downloading the build reproducer.sh from openstack jobs and running it on one or more remote machines.