uses getBaseUrl() instead of getBasePath() to also work in dev-environments

problems occured sending the following header:

```
Link: <http://example.local/api/app_dev.php/users/2>; rel="members"
```

When using getBaseUrl() instead of getBasePath() there is no problem.
When using getBasePath() the route is not found by the matcher because of the additional app_dev.php