private _getEnvironmentTypeName() : string {

    let value: string;
    switch (this.context.environment.type) {
      case EnvironmentType.ClassicSharePoint:
        value = 'ClassicSharePoint';
        break;
      case EnvironmentType.Local:
        value = 'Local';
        break;
      case EnvironmentType.SharePoint:
        value = 'SharePoint';
        break;
      case EnvironmentType.Test:
        value = 'Test';
        break;
      default:
        value = 'Unknown';
        break;
    }

    return value;
  }

  private _getManifestProperties() : string {
    let props: string;
    props = '<ul>';

    for (var index = 0; index < this.context.manifest.properties.length; index++) {
      var element = this.context.manifest.properties[index];
      props = props + '<li>' + element + '</li>';
    }


    props = props + '</ul>';

    return props;
  }