feat(SebmGoogleMap): support double-click event

Now, you can subscribe to double-click events:

```
<sebm-google-map
  [latitude]="lat"
  [longitude]="lng"
  (mapDblClick)="mapClicked($event)">
</sebm-google-map>
```

The $event is a `MapMouseEvent` type that contains
the coords of the double-click.

```
import {MapMouseEvent} from 'angular2-google-maps/core';

class App {
  mapClicked(event: MapMouseEvent) {
    console.log(event.coords.lat, event.coords.lng);
  }
}
```

docs/api/components_directives/sebmGoogleMap.md

@@ -32,10 +32,11 @@ import {SebmGoogleMap} from 'angular2-google-maps/core';
 
 ### Events
 
-| Event name | Arguments | Description |
-|---------------|---------------------------------|----------------------------------------------------------|
-| mapClick | [MapMouseEvent](#MapMouseEvent) | Gets emitted when the user clicks on the map |
-| mapRightClick | [MapMouseEvent](#MapMouseEvent) | Get emitted when the user uses a right click on the map. |
+| Event name | Arguments | Description |
+|---------------|---------------------------------|-------------------------------------------------------------------------------------------------------------------------------------|
+| mapClick | [MapMouseEvent](#MapMouseEvent) | Gets emitted when the user clicks on the map |
+| mapRightClick | [MapMouseEvent](#MapMouseEvent) | Gets emitted when the user uses a right click on the map. |
+| mapDblClick | [MapMouseEvent](#MapMouseEvent) | Gets emitted when the user double-clicks on the map. Note that the `mapClick` event emitter will also fire, right before this one. |
 
 ### Event Interfaces
 

src/directives/google-map.ts

@@ -30,6 +30,7 @@ export class SebmGoogleMap {
 
  @Output() mapClick: EventEmitter<MapMouseEvent> = new EventEmitter<MapMouseEvent>();
  @Output() mapRightClick: EventEmitter<MapMouseEvent> = new EventEmitter<MapMouseEvent>();
+ @Output() mapDblClick: EventEmitter<MapMouseEvent> = new EventEmitter<MapMouseEvent>();
 
  constructor(elem: ElementRef, _mapsWrapper: GoogleMapsAPIWrapper, renderer: Renderer) {
  this._mapsWrapper = _mapsWrapper;
@@ -106,7 +107,8 @@ export class SebmGoogleMap {
 
  const events: Event[] = [
  {name: 'click', emitter: this.mapClick},
- {name: 'rightclick', emitter: this.mapRightClick}
+ {name: 'rightclick', emitter: this.mapRightClick},
+ {name: 'dblclick', emitter: this.mapDblClick}
  ];
 
  events.forEach((e: Event) => {