feat(clear): when setting value to falsy, datepicker will clear, and …

…added demo

#11

demo/src/app/simple/simple.component.html

@@ -9,6 +9,7 @@
   <div class="col s6 right-align">
     <br/>
     <button type="button" class="ngx-daterangepicker-action waves-effect waves-light btn" (click)="open($event)">open from a button</button>
+    <button type="button" *ngIf="selected && selected.startDate" class="ngx-daterangepicker-action waves-effect waves-light btn red" (click)="clear($event)">Clear</button>
   </div>
 </div>
 <div class="row">

demo/src/app/simple/simple.component.ts

@@ -34,4 +34,8 @@ export class SimpleComponent implements OnInit {
   open(e) {
     this.pickerDirective.open(e);
   }
+  clear(e) {
+    // this.picker.clear(); // we can do
+    this.selected = null; // now we can do
+  }
 }

src/daterangepicker/daterangepicker.directive.ts

@@ -236,7 +236,7 @@ export class DaterangepickerDirective implements OnInit, OnChanges, DoCheck {
         this._el.nativeElement.value = this.picker.chosenLabel;
       }
     } else {
-      //
+      this.picker.clear();
     }
   }
     /**