allow single @inject annotations on methods

I'm converting my project with >1000 annotated services and even more annotated methods to this bundle. 
most of our methods are annotated with single @inject annotation. 
for convenience i've implemented the option to use a single annotation, if the method in question only expects one parameter.

so this is valid now:
```
/**
 * @Inject('service_name')
 */
public function setService(SomeService $service) {
}
```