* Add encrypted and kms_key_id arguments to the ebs_* and root_* block device configuration blocks

This commit resolves #6

* Updated example to include volume encryption settings

Field `owners` is required for `aws_ami`, otherwise it fails

Signed-off-by: Denis Iskandarov <d.iskandarov@gmail.com>

Signed-off-by: Denis Iskandarov <d.iskandarov@gmail.com>

* ability to append numerical suffix even to 1 instance
Signed-off-by: Denis Iskandarov <d.iskandarov@gmail.com>

* include use_num_suffix in README.md

* Allow specifying a list of subnet IDs to iterate instances over

* Include the module version and some code formatting

* Explicitly specify the version for SG AWS module