fix(datepicker): added ngOnChanges hook

closes #543

components/datepicker/datepicker-inner.component.ts

@@ -1,4 +1,4 @@
-import {Component, OnInit, EventEmitter, Input} from '@angular/core';
+import {Component, OnInit, EventEmitter, Input, OnChanges} from '@angular/core';
 import {
  CORE_DIRECTIVES, FORM_DIRECTIVES, NgClass, NgModel
 } from '@angular/common';
@@ -48,7 +48,7 @@ const SHORTCUT_PROPAGATION = false;
  `,
  directives: [FORM_DIRECTIVES, CORE_DIRECTIVES, NgClass, NgModel]
 })
-export class DatePickerInnerComponent implements OnInit {
+export class DatePickerInnerComponent implements OnInit, OnChanges {
  @Input() public datepickerMode:string;
  @Input() public startingDay:number;
  @Input() public yearRange:number;
@@ -97,7 +97,6 @@ export class DatePickerInnerComponent implements OnInit {
 
  public set activeDate(value:Date) {
  this._activeDate = value;
- this.refreshView();
  }
 
  // todo: add formatter value to Date object
@@ -131,7 +130,10 @@ export class DatePickerInnerComponent implements OnInit {
  } else if (this.activeDate === undefined) {
  this.activeDate = new Date();
  }
+ }
 
+ // this.refreshView should be called here to reflect the changes on the fly
+ public ngOnChanges():void {
  this.refreshView();
  }