Completion fixes

Use /etc/hosts in addtion to $HOME/.ssh/known_hosts as the source for
hostname completion

Turn on completion caching to speed up certain comands

When completing usernames, don't include system accounts by default

lib/completion.zsh

@@ -34,9 +34,31 @@ zstyle ':completion:*:*:*:*:processes' command "ps -u `whoami` -o pid,user,comm
 zstyle ':completion:*:cd:*' tag-order local-directories directory-stack path-directories
 cdpath=(.)
 
+# use /etc/hosts and known_hosts for hostname completion
+[ -r ~/.ssh/known_hosts ] && _ssh_hosts=(${${${${(f)"$(<$HOME/.ssh/known_hosts)"}:#[\|]*}%%\ *}%%,*}) || _ssh_hosts=()
+[ -r /etc/hosts ] && : ${(A)_etc_hosts:=${(s: :)${(ps:\t:)${${(f)~~"$(</etc/hosts)"}%%\#*}##[:blank:]#[^[:blank:]]#}}} || _etc_hosts=()
+hosts=(
+  "$_ssh_hosts[@]"
+  "$_etc_hosts[@]"
+  `hostname`
+  localhost
+)
+zstyle ':completion:*:hosts' hosts $hosts
+
+# Use caching so that commands like apt and dpkg complete are useable
+zstyle ':completion::complete:*' use-cache 1
+zstyle ':completion::complete:*' cache-path ~/.oh-my-zsh/cache/
+
+# Don't complete uninteresting users
+zstyle ':completion:*:*:*:users' ignored-patterns \
+        adm amanda apache avahi beaglidx bin cacti canna clamav daemon \
+        dbus distcache dovecot fax ftp games gdm gkrellmd gopher \
+        hacluster haldaemon halt hsqldb ident junkbust ldap lp mail \
+        mailman mailnull mldonkey mysql nagios \
+        named netdump news nfsnobody nobody nscd ntp nut nx openvpn \
+        operator pcap postfix postgres privoxy pulse pvm quagga radvd \
+        rpc rpcuser rpm shutdown squid sshd sync uucp vcsa xfs
+
+# ... unless we really want to.
+zstyle '*' single-ignored show
 
-# Load known hosts file for auto-completion with ssh and scp commands
-if [ -f ~/.ssh/known_hosts ]; then
-  zstyle ':completion:*' hosts $( sed 's/[, ].*$//' $HOME/.ssh/known_hosts )
-  zstyle ':completion:*:*:(ssh|scp):*:*' hosts `sed 's/^\([^ ,]*\).*$/\1/' ~/.ssh/known_hosts`
-fi