Adding dereference.circular option for avoiding stack overflow exception

[ELymar]

This is for Issue 63

63

The infinite recursion exception can be avoided by setting the dereference.circular option to "Ignore" in config.json file. For more info: https://apitools.dev/swagger-parser/docs/#circular-refs

Also a npm run fmt introduced some other changes

Sample usage in config:

    {
      "url":"http://localhost/swagger/docs/v1",
      "dereference": {
        "circular": "ignore"
      }
    },

[ELymar]

@fabsrc mind taking a look? Would be useful to avoid the exception.