Feature Request: Change the permission of a note

There is no easy way to change note's permission in mass. While I can mass import Markdown note with this CLI, I cannot seem to control the permission of those notes with CLI. And it is a painstakingly long process to do it one-by-one on the web GUI.

It would be great if there is a command like this:
```
hackmd-cli chmod [NOTEID] [[-r|--readable] [owner|login|everyone]] [[-w|--writable] [owner|login|everyone]]
```

Example,
```
$ hackmd-cli chmod some-note-id -r everyone -w login
Permission of your note https://hackmd.io/some-note-id has changed.
Readable: everyone
Writable: login
```