Clean up raw policy stats in account stat

Storage policy stats was not well parsed in account stat. This
patch parses the stats and print out the stats in a format like below:

$swift -A http://swift_cluster/auth/v1.0 -U test:tester -K testing stat
                   Account: AUTH_test
                Containers: 5
                   Objects: 1
                     Bytes: 2097152
Objects in policy "golden": 1
 Bytess in policy "golden": 2097152
Objects in policy "silver": 0
  Bytes in policy "silver": 0
               X-Timestamp: 1404697760.88809
                X-Trans-Id: txec519e24b44a413abb705-0053da2dcb
              Content-Type: text/plain; charset=utf-8
             Accept-Ranges: bytes

Change-Id: I7ad0ee6d88f8393e3a93e90cd52b9b592da7072d
Merge "Clean up raw policy stats in account stat"