采用upgrader，具体文章参考：
http://doc.gitlab.com/ce/update/upgrader.html
注意要事先安装一下依赖文件：
sudo apt-get install -y build-essential zlib1g-dev libyaml-dev libssl-dev libgdbm-dev libreadline-dev libncurses5-dev libffi-dev curl openssh-server redis-server checkinstall libxml2-dev libxslt-dev libcurl4-openssl-dev libicu-dev logrotate python-docutils pkg-config cmake
然后要参考这篇文章修改ruby gems安装镜像站点：
http://blog.csdn.net/csfreebird/article/details/37330591
如果遇到问题i，回到手动升级方式，参考文档：
http://doc.gitlab.com/ce/update/patch_versions.html