参考： http://blog.csdn.net/shiren1118/article/details/7761203
github上的版本和本地版本冲突的解决方法
$ git push XXX master
把本地master分支的最新修改推送至远程库XXX
Username for 'https://github.com': shiren1118
Password for 'https://shiren1118@github.com':
To https://github.com/shiren1118/iOS_code_agile.git
! [rejected] master -> master (non-fast-forward)
error: failed to push some refs to 'https://github.com/shiren1118/iOS_code_agile.git'
hint: Updates were rejected because the tip of your current branch is behind
hint: its remote counterpart. Merge the remote changes (e.g. 'git pull')
hint: before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.
勾选强制覆盖已有的分支（可能会丢失改动），再点击上传，上传成功。
[master][~/Downloads/ios] $ git push XXX master -f