参考博客:http://ihower.tw/blog/archives/3843
http://www.cnblogs.com/kym/archive/2010/08/12/1797937.html
http://gitbook.liuhui998.com/4_2.html(必看)
http://my.oschina.net/MinGKai/blog/142517
http://stackoverflow.com/questions/18930527/difference-between-git-pull-and-git-pull-rebase