Output template variables as single JSON

Currently, when both -DdebugModels and -DdebugOperations are used, template variables are output as separate JSONs.

If they are merged as a single JSON, it would be easier for developers to use their favorite template engines, such as EJS. Actually, I am having a hard time writing mustache templates to match our own client HTTP library, and I am starting to use EJS.

I am using this modification to accomplish this. https://github.com/swagger-api/swagger-codegen/compare/master...kenjitayama:singleJSONDebugInfo

For this use case, output would be input for other scripts, not just for debug information. So maybe an option like --outputTemplateVariables (without needing -DdebugModels and -DdebugOperations) would make more sense.

How do you think of this kind of output?