Add export as m3u button to playlist

ui/src/dataProvider/index.js

@@ -1,3 +1,6 @@
+import httpClient from './httpClient'
 import wrapperDataProvider from './wrapperDataProvider'
 
+export { httpClient }
+
 export default wrapperDataProvider

ui/src/dataProvider/wrapperDataProvider.js

@@ -1,9 +1,8 @@
 import jsonServerProvider from 'ra-data-json-server'
 import httpClient from './httpClient'
+import { REST_URL } from '../consts'
 
-const restUrl = '/app/api'
-
-const dataProvider = jsonServerProvider(restUrl, httpClient)
+const dataProvider = jsonServerProvider(REST_URL, httpClient)
 
 const mapResource = (resource, params) => {
   switch (resource) {