Remove the default bes_ssh_key_users variable

Add it as a requirement in the README.

roles/configure-bes/README.md

@@ -15,6 +15,10 @@ This role connects to bes and templates in a preseed file for installing an OS
 
   ```A UNIX crypted password for emergency keyboard access. Probably best to be a password you can type by hand on a crummy terminal (think VMWare remote console)```
 
+- bes_ssh_key_users
+
+  ```The list of users that you want to install the ssh keys for.```
+
 ## Running
 This role needs to be run as a user that has access to bes to change the install files for the hosts being worked on.
 eg

roles/configure-bes/defaults/main.yml

@@ -13,5 +13,3 @@ bes_grub_dev: /dev/sda
 bes_install_repo_server: www-uxsup.csx.cam.ac.uk
 
 bes_install_repo_dir: /pub/linux/ubuntu
-
-bes_ssh_key_users: "{{ ssh_key_users }}"