Astade for Ubuntu is available at Launchpad. There you can find two package archives for stable releases and for daily builds. Just follow the Launchpad instructions on how to add the archive of your choice to your system.
Here is the short version for the stable release archive:
That's all.
Behind a proxy you need:
export http_proxy=http://<proxy>:<port> export https_proxy=http://<proxy>:<port> sudo -E apt-add-repository ppa:astade/release
For adding the ppa.