More refactor work, removed useless code in instr and analysis, and refactor the readme
More refactor work, removed useless code in instr and analysis, and refactor the readme

columbia/xtern,columbia/xtern,hemingcui/xtern_with_paxos,columbia/xtern,columbia/xtern,columbia/xtern,hemingcui/xtern_with_paxos,columbia/xtern,hemingcui/xtern_with_paxos,hemingcui/xtern_with_paxos,hemingcui/xtern_with_paxos