Add cmd line switch to create CloudWatch alarms

-a switch creates CloudWatch alarms for existing SNS topics.

* CPU utilization
* Physical memory utilization
* Disk space utilization
* Instance status checks

User requires following permissions:
"cloudwatch:PutMetricAlarm",
"cloudwatch:PutMetricData",
"sdb:ListDomains",
"ec2:DescribeInstances"
Fix bug where alarm is only created for last disk in multi-disk systems

Add disk name to alarm name to stop new alarms overwriting old ones.
Partial conversion to AWS SDK v2 structure

Use of .With is obsolete.
Merge pull request #1 from tom-paine/add-cloudwatch-alarms

Add cmd line switch to create CloudWatch alarms