Simplify url_basename

Use urlparse from the standard library.

youtube_dl/utils.py

@@ -1092,7 +1092,5 @@ def remove_start(s, start):
 
 
 def url_basename(url):
-    m = re.match(r'(?:https?:|)//[^/]+/(?:[^?#]+/)?([^/?#]+)/?(?:[?#]|$)', url)
-    if not m:
-        return u''
-    return m.group(1)
+    path = compat_urlparse.urlparse(url).path
+    return path.strip(u'/').split(u'/')[-1]