Validate cli tool should accept multi-files or directories

[freenerd]

A side-effect of https://github.com/mapbox/cloudfriend/pull/31 is that validate-template cloudformation/*.js doesn't work anymore. Some ways of mitigating:

1. validate-template cloudformation/template1.js && validate-template cloudformation/template2.js
2. Allow validate-template cloudformation/ and loop over the template in /bin/validate-template.js
3. Revert https://github.com/mapbox/cloudfriend/pull/31 to use --region instead.

I think I'd prefer option 3, since it's the most compatible with how aws-cli works (which in a way is the godfather convention here).

/cc @rclark @vsmart

[vsmart]

Can you clarify what error you are seeing? I cannot reproduce.