安装教程链接：
http://wiki.rabbitvcs.org/wiki/install/ubuntu#adding-the-ppa
注意事项：
Hardy, Intrepid and Jaunty
Add the following line to your /etc/apt/sources.list file (signing key=1024R/34EF4A35):
deb http://ppa.launchpad.net/rabbitvcs/ppa/ubuntu **DISTRIBUTION** main
需要将**DISTRIBUTION** 改为版本号
deb http://ppa.launchpad.net/rabbitvcs/ppa/ubuntu trusty main