Run experiment from reprounzip

Currently, reprounzip sets up the experiment along with some kind of startup script, and it's up to the user to run that again. This has some caveats:

* Running the experiment is different depending on the unpacker (might need root, might not, might need to run vagrant and use an SSH client)
* Switching input files is hard (you need to look at or change the command line in the script, and optionally upload your new data in the container/virtual machine)
* Even if output files locations were displayed (#41), they are still in the container/virtual machine

Since I'll probably have to write code to do these steps for the VisTrails plugin (#8), I might as well put that in reprounzip.

* New command to start the experiment -- should this be an option to unpack? What happens if already unpacked? Running will certainly need the config, but we can extract that.
* Add starting logic for each container (implies su/sudo detection, SSH with [paramiko](https://github.com/paramiko/paramiko))
* Interface for specifying inputs/outputs to copy in/out (cli)
* Copying files (only a problem for Vagrant; use [scp.py](https://github.com/jbardin/scp.py)?)