Disable putting filter block to block cache

Summary: This bug caused server crash issues because the filter block is too big and kept purging out of cache.

Test Plan: Wrote a new unit tests to make sure it works.

Reviewers: dhruba, haobo, igor, sdong

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D16221
Add a test in prefix_test to verify correctness of results

Summary:
Add a test to verify HashLinkList and HashSkipList (mainly for the former one) returns the correct results when inserting the same bucket in the different orders.

Some other changes:
(1) add the test to test list
(2) fix compile error
(3) add header

Test Plan: ./prefix_test

Reviewers: haobo, kailiu

Reviewed By: haobo

CC: igor, yhchiang, i.am.jin.lei, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D16143
Update to CONTRIBUTING.md
allow lambda function syntax in cpplint

Summary: as title

Test Plan: arc lint

Reviewers: kailiu

Reviewed By: kailiu

CC: leveldb

Differential Revision: https://reviews.facebook.net/D16251