Update completion for SSH

Add all hosts found in ~/.ssh/config.
Tip found on: http://www.nerux.org/wiki/OpenSSH#coupler_avec_zsh_completion

lib/completion.zsh

@@ -33,14 +33,17 @@ cdpath=(.)
 
 # use /etc/hosts and known_hosts for hostname completion
 [ -r ~/.ssh/known_hosts ] && _ssh_hosts=(${${${${(f)"$(<$HOME/.ssh/known_hosts)"}:#[\|]*}%%\ *}%%,*}) || _ssh_hosts=()
+[ -r ~/.ssh/config ] && _ssh_config=($(cat ~/.ssh/config | sed -ne 's/Host[=\t ]//p')) || _ssh_config=()
 [ -r /etc/hosts ] && : ${(A)_etc_hosts:=${(s: :)${(ps:\t:)${${(f)~~"$(</etc/hosts)"}%%\#*}##[:blank:]#[^[:blank:]]#}}} || _etc_hosts=()
 hosts=(
+  "$_ssh_config[@]"
   "$_ssh_hosts[@]"
   "$_etc_hosts[@]"
   `hostname`
   localhost
 )
 zstyle ':completion:*:hosts' hosts $hosts
+zstyle ':completion:*' users off
 
 # Use caching so that commands like apt and dpkg complete are useable
 zstyle ':completion::complete:*' use-cache 1