ENH: Add support for injecting into Map<String,T> (by qualifier)

[rbygrave]

Inject map of beans keyed by qualifier name.

@Singleton
public class CombinedMapSomei {

  private final Map<String, Somei> somes;

  /**
   * Inject map of beans keyed by qualifier name.
   */
  @Inject
  public CombinedMapSomei(Map<String, Somei> somes) {
    this.somes = somes;
  }

Get dependencies as a map keyed by qualifier name

      SomeStore greenStore = beanScope.get(SomeStore.class, "green");
      SomeStore blueStore = beanScope.get(SomeStore.class, "blue");

      // get dependencies as a map keyed by qualifier name
      Map<String, SomeStore> stores = beanScope.map(SomeStore.class);

      SomeStore green = stores.get("green");
      assertThat(green).isSameAs(greenStore);
      SomeStore blue = stores.get("blue");
      assertThat(blue).isSameAs(blueStore);