The current implementation was broken (it did not always close dir handlers).

Removing this method also permit us to remove the following dependencies:
- Babel 5 (very old and unmaintained)
- Bluebird

- SMB method and params are injected
- synchronously created for better stack traces

Similar to 4b8f5754

Similar to 4b8f5754

`flag` option is also supported for `fs` compatibility

Test pre-condition can leads to race-conditions.
Also current code was hiding SMB error.

And fix `new Buffer()` uses.

Having `.name` property defined helps for debugging.

Async methods return promises if no callbacks is passed.