Checks for the path in ``_revCache`` and decides based on that if file
has changed.

Compatible with ``WireClient.delete``

Calls ``Dropbox.share`` afterwards to fill ``_itemRefs``.

@param {string} path - path of the folder to delete, with leading slash
@param {Object} options

@protected
function (path, options) {
    if (!this.connected) {
      throw new Error("not connected (path: " + path + ")");
    }

    //check if file has changed and return 412
    var savedRev = this._revCache.get(path);
    if (options && options.ifMatch && savedRev && (options.ifMatch !== savedRev)) {
      return Promise.resolve({ statusCode: 412, revision: savedRev });
    }

    if (options && options.ifMatch) {
      return this._getMetadata(path).then((metadata) => {
        if (options && options.ifMatch && metadata && (metadata.rev !== options.ifMatch)) {
          return Promise.resolve({
            statusCode: 412,
            revision: metadata.rev
          });
        }

        return this._deleteSimple(path);
      });
    }

    return this._deleteSimple(path);
  }