Add Japanese keymap

Just add Japanese keymap.

However, I concern about keymap code. In Japanese Windows environment, keymap code may take multiple value, 0x00000411, 0x00100411, 0x02000411, 0x02100411, depends on avtive input method.

It will be defined like this in xrdp_keyboard.ini. We need to make some more changes to xrdp in order to recognize such keyboard definition, IMHO.  

```
[default_rdp_layouts]
rdp_layout_jp=0x00000411|0x00100411|0x02000411|0x02100411
```

@jsorg71 What do you think?