[systemd] Setup systemd to manage user session.
[xmonad] Removed conky start-up dependency (now managed by systemd).
[xorg] Removed init script (now managed by systemd).
[systemd] Clean-up global configuration.
[git] Set nano as default editor.
[slim] Updated to start systemd at login to manage user session.
[pam] Updated slim configuration to work with systemd.