(WIP) Add put-metric-alarm command

Following naming convention in http://docs.aws.amazon.com/cli/latest/reference/cloudwatch/index.html
In principle it should be possible, but for now I'm copying from `put-metric.hs` (now `put-metric-data.hs`) to make something that works first. I'm also running into a funny problem where `auto` can't seem to parse strings.