Changes default directory to "."

This Pull Request changes the default search path from `*` to `.`.  The former causes errors on OS X:

````
$: search 'foo' -r

fs.js:679
  return binding.lstat(pathModule._makeLong(path));
                 ^
Error: ENOENT, no such file or directory '*'
    at Object.fs.lstatSync (fs.js:679:18)
    at replacizeFileSync (/Users/jeremyckahn/Sites/node/replace/replace.js:110:22)
    at module.exports (/Users/jeremyckahn/Sites/node/replace/replace.js:53:13)
    at Object.<anonymous> (/Users/jeremyckahn/Sites/node/replace/bin/search.js:11:1)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Function.Module.runMain (module.js:497:10)
    at startup (node.js:119:16)
````

This change allows users to omit the path and still get useful results.