Changes from Parse

small changes:
* optionally use a config file instead of command line arguments to start mongo
* optionally suppress server restarts on config change (sometimes you want to
  restart production servers more carefully)
* if ganglia is installed, report metrics
* make the replicaset prefix "rs_" customizable via attribute
* add ubuntu as a platform and use upstart when on ubuntu
big changes:
* new recipe to backup mongo using ec2-consistent-snapshot
* new recipe to put the mongo db mountpoint on a set of raided EBS volumes
** when using raided EBS volumes, automatically start new instances
   using snapshots to make joining the cluster fast and easy