How to enable hibernation in 15.04?

1. Create the following file: /etc/polkit-1/localauthority/10-vendor.d/com.ubuntu.desktop.pkla

2. Copy / paste the following content into it:

   [Enable hibernate by default in upower]
   Identity=unix-user:*
   Action=org.freedesktop.upower.hibernate
   ResultActive=yes
   
   [Enable hibernate by default in logind]
   Identity=unix-user:*
   Action=org.freedesktop.login1.hibernate;org.freedesktop.login1.handle-hibernate-key;org.freedesktop.login1;org.freedesktop.login1.hibernate-multiple-sessions;org.freedesktop.login1.hibernate-ignore-inhibit
   ResultActive=yes
   

3. Log out and check that you can see the hibernate menu item on the login screen, do the same once you logged in.

The reason the above manual step needs to be done is that they seem to have disabled hibernate by default in Ubuntu 15.04.