Debian Jessie

Install using the default package version of Deluge (this means you won't get an up to date version, but it'll be updated automatically with your system)

Install Deluge (GUI)

apt-get install deluge

Install (headless/server)

apt-get install deluged deluge-web

Deluge Launchpad PPA

Install using the Deluge Ubuntu Launchpad PPA which contains the latest releases of Deluge and libtorrent.

add-apt-repository 'deb http://ppa.launchpad.net/deluge-team/ppa/ubuntu trusty main'
apt-get update
apt-get install -t trusty deluged deluge-web

To upgrade libtorrent:

apt-get install -t trusty libtorrent-rasterbar8 python-libtorrent

For config and systemd service setup see UserGuide/InitScript/systemd and UserGuide/ThinClient.