Update gunicorn from 19.8.1 to 19.9.0

Author: pyup-bot

requirements/default.txt

@@ -94,9 +94,9 @@ gevent==1.3.7 \
     --hash=sha256:d26b57c50bf52fb38dadf3df5bbecd2236f49d7ac98f3cf32d6b8a2d25afc27f \
     --hash=sha256:298a04a334fb5e3dcd6f89d063866a09155da56041bc94756da59db412cb45b1 \
     --hash=sha256:3f06f4802824c577272960df003a304ce95b3e82eea01dad2637cc8609c80e2c
-gunicorn==19.8.1 \
-    --hash=sha256:7ef2b828b335ed58e3b64ffa84caceb0a7dd7c5ca12f217241350dec36a1d5dc \
-    --hash=sha256:bc59005979efb6d2dd7d5ba72d99f8a8422862ad17ff3a16e900684630dd2a10
+gunicorn==19.9.0 \
+    --hash=sha256:aa8e0b40b4157b36a5df5e599f45c9c76d6af43845ba3b3b0efe2c70473c2471 \
+    --hash=sha256:fa2662097c66f920f53f70621c6c58ca4a3c4d3434205e608e121b5b3b71f4f3
 html5lib==1.0.1 \
     --hash=sha256:20b159aa3badc9d5ee8f5c647e5efd02ed2a66ab8d354930bd9ff139fc1dc0a3 \
     --hash=sha256:66cb0dcfdbbc4f9c3ba1a63fdb511ffdbd4f513b2b6d81b80cd26ce6b3fb3736