No "resource" property support

[Maxim-Mazurok]

For example, batchUpdate() in spreadsheets has

"request": {
  "$ref": "BatchUpdateSpreadsheetRequest"
}

to specify the type of POST-request body.
It can be specified either by resource property in the object that you pass to batchUpdate() or as a second argument.
Currently, this generator doesn't handle it.
Related info: google/google-api-javascript-client#432 (comment)

[Maxim-Mazurok]

Closed by accident. Reopened here: #10