Extend REST api for baskets and fairteiler
Most requests are done via the Xhr api and up to now the REST api does only include some of the features. It should be extended by functions for baskets, fairteiler, and maybe some more to have a more modern api and to support the Android/iOS apps. Also, in some cases HTML/JS is included in the response data (e.g. the 'bubbles' for baskets on the map) which makes is difficult to use the data in an app.
The website will continue to run on the Xhr, so it should not have any impact on the website or users yet. In the long term it might be an idea to replace Xhr with Rest.
Add functions for:
- list, add, and delete baskets
- list fairteiler