Call addonpath from jsonrcp

Shouldnt have to use Player.Open
Example:
```
cmd = {
            'jsonrpc': '2.0',
            'id': 0,
            'method': 'Addons.ExecuteAddon',
            'params': {
                'addonid': 'plugin.video.nrk',
                'params': {
                    'path' : '/category/barn'
                }
            }
        }
```