We recommend running Fedora (the Linux OS; you can get it here). With Fedora running, you can install DevAssistant simply by executing
# yum install devassistant
in the command line or installing devassistant through Yum-Extender or Gnome-PackageKit by searching for devassistant.
DevAssistant is available for download via pip, the Python package installer. If your operating system has a package manager, you can install pip with it (precise method depends on your OS). The package is usually named pip or python-pip. If your system doesn't have a package manager, you can download pip.
$ pip install devassistant
Bear in mind, though, that you don't get automatic updates with pip as opposed to the option above.
To check out the DevAssistant repository (read only), make sure you have git installed and run
git clone https://github.com/devassistant/devassistant.git
If you prefer to download a tarball, you can get it here: (latest commit; for tagged releases and/or downloading the source from a different branch, you can browse the repository)