Make default cursor start at now-70m instead of now-10m.

The file feed has a 1 hour delay, which means that files submitted now won't be available until 1 hour later. For this reason initializing the cursor as now-10m does't make sense as you would have to wait for 50 minutes for the first result to appear. Staring at now-70m makes more sense.

vt/feed.py

@@ -79,7 +79,7 @@ def __init__(self, client, feed_type, cursor=None):
       self._batch_time = datetime.strptime(batch_time, '%Y%m%d%H%M')
       self._batch_skip = int(batch_skip) if batch_skip else 0
     else:
-      self._batch_time = datetime.utcnow() - timedelta(minutes=10)
+      self._batch_time = datetime.utcnow() - timedelta(minutes=70)
       self._batch_skip = 0
 
     self._next_batch_time = self._batch_time