Remove placement.db.base

It's not used in placement and was lost in the shuffle while
doing the extraction.

Change-Id: If5ad378734e483c084b55af2f7b0bf1a71112b21

placement/db/base.py

@@ -1,27 +0,0 @@
-# Copyright 2010 United States Government as represented by the
-# Administrator of the National Aeronautics and Space Administration.
-# All Rights Reserved.
-#
-#    Licensed under the Apache License, Version 2.0 (the "License"); you may
-#    not use this file except in compliance with the License. You may obtain
-#    a copy of the License at
-#
-#         http://www.apache.org/licenses/LICENSE-2.0
-#
-#    Unless required by applicable law or agreed to in writing, software
-#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-#    License for the specific language governing permissions and limitations
-#    under the License.
-
-"""Base class for classes that need database access."""
-
-import placement.db.api
-
-
-class Base(object):
-    """DB driver is injected in the init method."""
-
-    def __init__(self):
-        super(Base, self).__init__()
-        self.db = placement.db.api