fix flake8 complaints

dataset/database.py

@@ -130,7 +130,7 @@ class Database(object):
         if error_type is None:
             try:
                 self.commit()
-            except:
+            except Exception:
                 with safe_reraise():
                     self.rollback()
         else:

dataset/table.py

@@ -460,7 +460,7 @@ class Table(object):
                                   offset=_offset)
         if len(order_by):
             query = query.order_by(*order_by)
-        
+
         conn = self.db.executable
         if _streamed:
             conn = self.db.engine.connect()