Use bitset for BloomFilter.

Before:
(0)  660.00 (1.43%)
(1)  45320.00 (98.18%)
(2)  80.00 (0.17%)
Total 46160.00 (sum of others 46060.00)

After:
(0)  620.00 (1.34%)
(1)  45310.00 (98.05%)
(2)  130.00 (0.28%)
Total 46210.00 (sum of others 46060.00)

Change-Id: I936b639c50e15208aee999a929b33983c6caa59d