logging_when_create_and_delete_manifest

Summary:
  1. logging when create and delete manifest file
  2. fix formating in table/format.cc

Test Plan:
  make all check
  run db_bench, track the LOG file.

Reviewers: ljin, yhchiang, igor, yufei.zhu, sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D21009
Changes to support unity build:
* Script for building the unity.cc file via Makefile
* Unity executable Makefile target for testing builds
* Source code changes to fix compilation of unity build