Add feature to get Windows password generated by AWS

[zl4bv]

Rather than pre-determining the password for a Windows instance (baked AMI, set password in user-data, etc) it would be nice to be able to use the password generated automatically by AWS.

Example config:

---
driver:
  name: ec2
  aws_ssh_key_id: key_pair_name
  get_windows_password: true

transport:
  name: winrm
  username: Administrator
  ssh_key: /path/to/key_pair_name.pem

[tyler-ball]

Rather than adding a new config key, shouldn't we just fetch the password if they have supplied config[:username] =~ /[Aa]dministrator/ and haven't supplied config[:password]?

[zl4bv]

Yeah that makes more sense.

My concern is when this is used with a Linux instance with an SSH key (therefore not specifying a password). If we're happy to assume that someone running kitchen-ec2 with a Linux instance won't use a username matching /[Aa]dministrator/ then it should be fine.

[tyler-ball]

The driver has a windows_os? method that can tell if the instance its spinning up is a Windows instance

[tyler-ball]

Closing this as it was merged as part of #150