Fix redirections

The problem
===

Request  module was ignoring the new location

Why:
===

when there are a new redirection  self.uri is set  to the new location
```javascript
self.uri = url.parse(redirectTo)
```

after that again , call  the init function with this

```javascript
if (self.url ) {
    // People use this property instead all the time so why not just support it.
    self.uri = self.url
    delete self.url
  }
```
so the location is ignored, have not effect, and the second request is done to the original url

solution
===
```javascript
if (self.url && !self.uri) {
    // People use this property instead all the time so why not just support it.
    self.uri = self.url
    delete self.url
  }
```

Regards