Updated two shell and two python scripts:
  add_new_machine encloses $1 and $2 with double quotes now: $1 -> "$1"
  Removed some trailing whitespaces.
  spawn_ec2_instances is now using the absolute path to the ssh key and
  prompts for user input before committing and pushing to remote git
  repo.
  Fixed indentation of shell scripts.
  and some more work...