Get EBS volume type and whether or not encryption is enabled without using AWS::EC2::Client#describe_volumes

Its annoying to have to use the lower level client to have to check for these.

It wasn't clear how to handle the case where the volume didn't exist or how to add test cases to [volume_spec.rb](https://github.com/aws/aws-sdk-ruby/blob/master/spec/aws/ec2/volume_spec.rb) so if anyone has advice for how to do that I'd appreciate it.