[rtve] Add support for live stream

At the moment, only RTVE-1 seems to work flawlessly.
-2 seems geoblocked right now.
-TDP doesn't seem to be available outside of Spain.

youtube_dl/utils.py

@@ -1285,6 +1285,12 @@ def remove_start(s, start):
     return s
 
 
+def remove_end(s, end):
+    if s.endswith(end):
+        return s[:-len(end)]
+    return s
+
+
 def url_basename(url):
     path = compat_urlparse.urlparse(url).path
     return path.strip(u'/').split(u'/')[-1]