cli: fix tab completion

tab completion relies on a global 'ls' object, re-add it.

Broken by 4bfe157b.

console/cli.js

@@ -44,6 +44,7 @@ var MAX_LENGTH = 80;
 
 var cd = _commands.cd
 var run_cmd = _commands.run
+var ls = _commands.ls
 
 // Prompt
 _prompt = "[osv]$ ";