Installing Redmine from a package

To install Redmine from a package, we will use Debian jessie 8.2. Usually, I would recommend that you use Ubuntu server Long Term Support (LTS) instead. I would did this because it's more popular and has a larger community, but the Redmine version that comes with Ubuntu LTS is too outdated to be reviewed in this book (it's currently 2.4). However, Ubuntu LTS is largely based on the Debian stable repository, so the installation procedure should be the same for both systems (to make sure that it will be, I'm also going to use Ubuntu-style commands). Also, this in turn means that the very next Ubuntu LTS version is going to come with the version of Redmine that is currently shipped with Debian stable distribution. So, it can be said that we are going to use the future version of Ubuntu Server. Additionally, I personally prefer Debian stable over Ubuntu as the former is an older Linux distribution, is the original one, and has a more professional...