[enh] Initial no paging support for Yep.com

Upstream example query:
https://yep.com/web?q=test

https://yep.com/about

searx/engines/json_engine.py

@@ -16,6 +16,11 @@ paging = False
 suggestion_query = ''
 results_query = ''
 
+cookies = {}
+headers = {}
+'''Some engines might offer different result based on cookies or headers.
+Possible use-case: To set safesearch cookie or header to moderate.'''
+
 # parameters for engines with paging support
 #
 # number of results on each page
@@ -88,6 +93,9 @@ def request(query, params):
     if paging and search_url.find('{pageno}') >= 0:
         fp['pageno'] = (params['pageno'] - 1) * page_size + first_page_num
 
+    params['cookies'].update(cookies)
+    params['headers'].update(headers)
+
     params['url'] = search_url.format(**fp)
     params['query'] = query