Refactor setupEntries and export route

Refactor setupEntries

Export route to use middleware like this
```
    var myapp = express();
    myapp.use(stubcell.route);
    var server = myapp.listen(9000);
```

Require merge [stubrec](https://github.com/yosuke-furukawa/stubrec/pull/1)
OR change the sentences to other function like.

```javascript
var file = this.getFile(entryUrl, response);

Stubcell.prototype.getFile = function(entryUrl, response) {
  return response.file ?
        response.file.indexOf("/") === 0 ?
        response.file :
        path.join(this.basepath, response.file) :
        this.fileFromRequest(entryUrl, response.file, req, this.basepath);
};
```