Merge upstart and EBS changes from Parse.

This is only the upstart and EBS support parts of the Parse patch. I've removed the Ganglia stuff which we don't want. I've also removed the configurable `replicaset_prefix`, the option to `use_config_file` for starting the server, and the `should_restart_server` attribute that controls whether MongoDB should be restarted when pushing updates. We might want these last three, but I'd rather split them off.

This requires the updates to the AWS cookbook.