Update ad filter keywords

New changes to google search now include ads prefixed with the keyword
"sponsored". This update should remove these from appearing in search
results.

Fixes #871

app/utils/results.py

@@ -25,7 +25,7 @@ BLACKLIST = [
     'Reklama', 'Реклама', 'Anunț', '광고', 'annons', 'Annonse', 'Iklan',
     '広告', 'Augl.', 'Mainos', 'Advertentie', 'إعلان', 'Գովազդ', 'विज्ञापन',
     'Reklam', 'آگهی', 'Reklāma', 'Reklaam', 'Διαφήμιση', 'מודעה', 'Hirdetés',
-    'Anúncio', 'Quảng cáo','โฆษณา'
+    'Anúncio', 'Quảng cáo','โฆษณา', 'sponsored'
 ]
 
 SITE_ALTS = {