added autojump plugin support for mac os x + port

plugins/autojump/autojump.plugin.zsh

@@ -3,6 +3,8 @@ if [ $commands[autojump] ]; then # check if autojump is installed
     . /usr/share/autojump/autojump.zsh
   elif [ -f /etc/profile.d/autojump.zsh ]; then # manual installation
     . /etc/profile.d/autojump.zsh
+  elif [ -f /opt/local/etc/profile.d/autojump.zsh ]; then # mac os x with ports
+    . /opt/local/etc/profile.d/autojump.zsh
   elif [ $commands[brew] -a -f `brew --prefix`/etc/autojump ]; then # mac os x with brew
     . `brew --prefix`/etc/autojump
   fi