Process command line arguments

We now have:

  usage: ci-bootstrap.py [-h] (--create_droplet | --droplet_id ID) [--terminate]
                         [--verbose]

  Run bootstrap scriptto deploy Openappstack to a given node.

  optional arguments:
    -h, --help        show this help message and exit
    --create_droplet  Create droplet automatically
    --droplet_id ID   ID of droplet to deploy to
    --terminate       Terminate droplet after deploy
    --verbose         Be more verbose