Launching applications on machines

[sgpthomas]

We want to simplify the process of launching applications on machines. It will be an api call. We can either do this on the experiment object in Jupyter or in the run.py script. The call will be something like set_program('type', 'benchmark.py', num_servers, *args). During the launch phase, pydsef would automatically launch the programs on the correct machines with paramiko ssh module. During teardown, the launched programs will be automatically killed (maybe can do this just by closing the paramiko session). API needs discussion.