function GoogleStreetviewPanorama(panoId, apiKey) {
    ImagePanorama.call(this);

    this.panoId = panoId;

    this.gsvLoader = null;

    this.loadRequested = false;

    this.setupGoogleMapAPI(apiKey);
}
@classdesc Google streetview panorama
@description [How to get Panorama ID]{@link http://stackoverflow.com/questions/29916149/google-maps-streetview-how-to-get-panorama-id}
@constructor
@param {string} panoId - Panorama id from Google Streetview
@param {string} [apiKey] - Google Street View API Key