Towards new ami and etc

This needs some folks to try it out and reviewing before merging. /cc @chilts, @rfk, @dannycoates, @6a68, @callahad

Summary:

- builds new AMI images from scratch Amazon Linux 64 using @lloyd's cdist work
- minor doc fixes for cdist
- in building from scratch, a couple of things have changed that were addressed, notably the need for ssh.ensureSshAccessPerms to allow app@ to login again (note: changes to awsbox.js look large but are mostly indenting the existing pyramid :-) )
- fixes another place where deploys would abort on too much buffer data (49dc965)
All this code and no minor nit from me. I should fix that! :)

```
child_process.execFile(ssh, args, cb)
```

Feel free to ignore my annoying comment!