message: fix(server): use right TextFile interface path on FilesystemTextFile class
diff: // limitations under the License.
  import * as fs from 'fs';
  -import {TextFile} from '../model/text_file';
  +import {TextFile} from './text_file';
  // Reads a text file if it exists, or null if the file is not found.
  // Throws any other error except file not found.
  