WIP: Add initial restic support.

I've added a handler and example config file for restic. Since I'll be deploying this via Ansible, I'm not intending to write a helper, etc. But, I figured I'd share what basic progress I have made.

handlers/restic.in

@@ -23,7 +23,7 @@ if [ -z $password_file ]; then
    fatal "No password file specified."
 fi
 if [ ! -f $password_file ]; then
-   fatal "The specified password file does not exist."
+   fatal "The specified password file '$password_file' does not exist."
 fi
 
 getconf backup    "yes"