Angular-google-maps: GoogleMapsAPIWrapper is required to be passed as a provider

Issue description
When I try injecting GoogleMapsAPIWrapper into one of my components, I have to provide the Wrapper either to my NgModule or my NgComponent. This doesn't seem like expected behavior.
If this is an Angular 4 service, you should be able to just import AgmCoreModule and not have to use the providers array in your module.

Steps to reproduce and a minimal demo of the problem

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
constructor(googleMapsAPIWrapper: GoogleMapsAPIWrapper) { //

}
@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    FormsModule,
    AgmCoreModule.forRoot()
  ],
  providers: [  ], //wrong
  bootstrap: [AppComponent]
})
export class AppModule { }

The above gives an error.
You need to change to
providers: [ GoogleMapsAPIWrapper ], bootstrap: [AppComponent]

Expected/desired behavior
You shouldn't have to provide GoogleMapsAPIWrapper to your Module.

angular2 & angular-google-maps version
angular: 4.1.3

agm/core: 1.0.0-beta.0

Other information