Rename --cn-verfication-proxy to --geo-verification-proxy

And deprecate the former one

Since commit f138873900, this option is
not limited to China websites, so rename it.

youtube_dl/extractor/kuwo.py

@@ -26,11 +26,6 @@ class KuwoBaseIE(InfoExtractor):
     def _get_formats(self, song_id, tolerate_ip_deny=False):
         formats = []
         for file_format in self._FORMATS:
-            headers = {}
-            cn_verification_proxy = self._downloader.params.get('cn_verification_proxy')
-            if cn_verification_proxy:
-                headers['Ytdl-request-proxy'] = cn_verification_proxy
-
             query = {
                 'format': file_format['ext'],
                 'br': file_format.get('br', ''),
@@ -42,7 +37,7 @@ class KuwoBaseIE(InfoExtractor):
             song_url = self._download_webpage(
                 'http://antiserver.kuwo.cn/anti.s',
                 song_id, note='Download %s url info' % file_format['format'],
-                query=query, headers=headers,
+                query=query, headers=self.geo_verification_headers(),
             )
 
             if song_url == 'IPDeny' and not tolerate_ip_deny: