knife_ssh: small tweaks

plugins/knife_ssh/knife_ssh.plugin.zsh

 function knife_ssh() {
-  grep -q $1 ~/.knife_comp~ 2> /dev/null || rm -f ~/.knife_comp~;
+  grep -q $1 ~/.knife_comp~ 2> /dev/null || rm -f ~/.knife_comp~
   ssh $(knife node show $1 | awk '/IP:/{print $2}')
 }
 
 _knife_ssh() {
   if hash knife 2>/dev/null; then
     if [[ ! -f ~/.knife_comp~ ]]; then
-      echo "\nGenerating ~/.knife_comp~..." >/dev/stderr
+      echo "\nGenerating ~/.knife_comp~..." >&2
       knife node list > ~/.knife_comp~
     fi
-    compadd $(<~/.knife_comp~)
+    compadd $(< ~/.knife_comp~)
   else
-    echo "Could not find knife" > /dev/stderr;
+    echo "Could not find knife" >&2
   fi
 }