Add support for @Qualifier annotations (as alternative to @Named)

[rbygrave]

Create a qualifier annotation. e.g.

@Qualifier
@Retention(RUNTIME)
public @interface Blue {
}

Specify the qualifier annotation rather than @Named on beans and injection targets (constructor parameters, field injection).

@Blue
@Singleton
public class BlueStore implements SomeStore {
...

Constructor injection:

@Singleton
public class StoreManagerWithQualifier {

  private final SomeStore store;

  public StoreManagerWithQualifier(@Blue SomeStore store) {
    this.store = store;
  }

Field injection:

@Singleton
public class StoreManagerWithFieldQualifier {

  @Inject
  @Blue
  SomeStore store;