[traileraddict] Obtain hd quality stream if available

No clear method for determining if hd is available so opted to just
check for presence of hd toggle function.

youtube_dl/extractor/traileraddict.py

@@ -26,7 +26,13 @@ class TrailerAddictIE(InfoExtractor):
                 webpage, 'Views Count')
         video_id = self._og_search_property('video', webpage, 'Video id').split('=')[1]
 
-        info_url = "http://www.traileraddict.com/fvar.php?tid=%s" %(str(video_id))
+        # Presence of (no)watchplus function indicates HD quality is available
+        if re.search(r'function (no)?watchplus()', webpage):
+            fvar = "fvarhd"
+        else:
+            fvar = "fvar"
+
+        info_url = "http://www.traileraddict.com/%s.php?tid=%s" % (fvar, str(video_id))
         info_webpage = self._download_webpage(info_url, video_id , "Downloading the info webpage")
 
         final_url = self._search_regex(r'&fileurl=(.+)',