fixed youtube api change

it seems youtube changed their api,
and the npm-package we use passed that along to us. great!

Made adjustments to their api and improved user feedback
when no videos were found.

Closes #231

helpers.js

@@ -1132,11 +1132,16 @@ exports.kodiPlayYoutube = (request, response) => { // eslint-disable-line no-unu
         })).then((foundVideos) => {
 
             let items = foundVideos
-                .filter((video) => video.filetype === 'file')
+                .filter((video) => video.filetype === 'file' || video.kind === 'youtube#video')
                 .map((video) => ({
                     file: `plugin://plugin.video.youtube/play/?video_id=${video.id}`
                 }));
 
+            if (items.length === 0) {
+                console.log(foundVideos);
+                return new Error(`No playable videos found!`);
+            }
+
             console.log(`Playing ${items.length} youtube videos:`);
 
             return kodi.Playlist.Clear({ // eslint-disable-line new-cap
@@ -1259,6 +1264,18 @@ exports.kodiTogglePartymode = (request) => {
         .then((playerid) => togglePartyMode(kodi, playerid));
 };
 
+const getDirecoryContents = (kodi, path) => {
+    return kodi.Files.GetDirectory({ // eslint-disable-line new-cap
+        directory: path
+    })
+    .then((kodiResponse) => {
+        if (!(kodiResponse && kodiResponse.result && kodiResponse.result.files && kodiResponse.result.files.length > 0)) {
+            throw new Error('directory was empty');
+        }
+        return kodiResponse.result.files;
+    });
+};
+
 exports.kodiToggleFullscreen = (request) => { // eslint-disable-line no-unused-vars
     console.log('Toggle Fullscreen request received');
     let Kodi = request.kodi;