Implement title fetch in metadatafetch.py

A simple prototype for fetching the title of media using youtube-dl.

grzegorz/metadatafetch.py

@@ -0,0 +1,7 @@
+import youtube_dl
+from . import nyasync
+
+@nyasync.ify
+def title(url):
+    ydl = youtube_dl.YoutubeDL()
+    return ydl.extract_info(url, download=False).get('title')