Update autojump plugin for latest brew installation

plugins/autojump/autojump.plugin.zsh

@@ -15,7 +15,7 @@ if [ $commands[autojump] ]; then # check if autojump is installed
     . /usr/local/share/autojump/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.zsh ]; then # mac os x with brew
-    . `brew --prefix`/etc/autojump.zsh
+  elif [ $commands[brew] -a -f `brew --prefix`/etc/autojump.sh ]; then # mac os x with brew
+    . `brew --prefix`/etc/autojump.sh
   fi
 fi