[mod] add 'Accept-Language' HTTP header to online processores

Most engines that support languages (and regions) use the Accept-Language from
the WEB browser to build a response that fits to the language (and region).

- add new engine option: send_accept_language_header

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

searx/engines/google_videos.py

@@ -60,6 +60,7 @@ language_support = True
 use_locale_domain = True
 time_range_support = True
 safesearch = True
+send_accept_language_header = True
 
 RE_CACHE = {}
 
@@ -111,7 +112,6 @@ def request(query, params):
     """Google-Video search request"""
 
     lang_info = get_lang_info(params, supported_languages, language_aliases, False)
-    logger.debug("HTTP header Accept-Language --> %s", lang_info['headers']['Accept-Language'])
 
     query_url = (
         'https://'