[Feature Request] Add wildcard support for json files

Hello,

it would be cool if the wildcard is passed into the json files to, so { id: __project_uuid__ } will return the current uuid.

Maybe the wildcard needs some type of escaping, eg: $__project_uuid__$

This would reduce the usage of more complicated js files.

[BennyAlex]

But {"id": "__id__"} would be already nice and I think its okay to turn it on by default, but maybe the user can disable it with an option passed to the mock config

[BennyAlex]

yeah you are right. Another cool thing would be usage of simple expressions

{ 'doubleID': 'mockExpresion(__uuid__ * 2)' }

where ‘mockExpresion’ indicates the value is an expression