Bring gulp standard options to method

[qfox]

src(sources: String[], decl: BemEntityName[], techs: String|String[], [, options: {
  config: ?BemConfig, // Should be loaded from .bemrc by default
  techAliases: ?Object<String,String[]> // Should use aliases from .bemrc if any

  // vfs.src options:
  buffer: Boolean=true,
  read: Boolean=true,
  since: ?(Date|Number),
  stripBOM: Boolean=true,
  passthrough: Boolean=false,
  sourcemaps: Boolean=false,
  followSymlinks: Boolean=true, // we should pass it to bem-walk?
  dots: Boolean=false // pointless?,
  // etc.
}]): Stream<Vinyl>