generate-cli-skeleton argument would benefit all commands

I was unable to discern why the [generatecliskeleton](https://github.com/aws/aws-cli/blob/1.7.37/awscli/customizations/generatecliskeleton.py) customization does not apply to all aws-cli sub-commands. I didn't know if it was an oversight, or if it was explicitly excluded from commands for a reason.

For example, one will observe that `cloudformation` [get-template](http://docs.aws.amazon.com/cli/latest/reference/cloudformation/get-template.html) has both `--generate-cli-skeleton` and the consumer `--cli-input-json`, but `emr` [create-cluster](http://docs.aws.amazon.com/cli/latest/reference/emr/create-cluster.html), on the other hand, does not honor it even though it has way more options and thus would benefit from it more.

Unless there is a reason, it would be absolutely great to have those two arguments accepted by all aws-cli commands, to reduce the amount of shell quoting and "pseudo DSL" use in the option parsing.