Crowdin synchronisation script

Added a script that provides synchronisation between crowdin and the 3akai-ux codebase. This script can be run by the following command:

```
node sync.js -a <crowdinAPIKey> -r <3akai-ux root dir>
```

The synchronisation script will also republish all manifest.json files to reflect the available languages for each widget.

Next to that, this PR also contains the following changes:

- Latest translation from Crowdin (100% Dutch, 100% French, 100% German, 100% Spanish + additional Catalan and Chinese)
- Change to the widget manifest.json format. The i18n property is now supposed to be an array of available language codes, rather than an object with bundle URLs