fix(datepicker): change to higher max date

- Change to higher max date so there are valid dates to choose from in the demo

Closes #4042

src/datepicker/docs/demo.html

@@ -22,7 +22,7 @@ <h4>Popup</h4>
     <div class="row">
         <div class="col-md-6">
             <p class="input-group">
-              <input type="text" class="form-control" datepicker-popup="{{format}}" ng-model="dt" is-open="opened" min-date="minDate" max-date="'2015-06-22'" datepicker-options="dateOptions" date-disabled="disabled(date, mode)" ng-required="true" close-text="Close" />
+              <input type="text" class="form-control" datepicker-popup="{{format}}" ng-model="dt" is-open="opened" min-date="minDate" max-date="'2020-06-22'" datepicker-options="dateOptions" date-disabled="disabled(date, mode)" ng-required="true" close-text="Close" />
               <span class="input-group-btn">
                 <button type="button" class="btn btn-default" ng-click="open($event)"><i class="glyphicon glyphicon-calendar"></i></button>
               </span>
@@ -31,7 +31,7 @@ <h4>Popup</h4>
 
         <div class="col-md-6">
             <p class="input-group">
-              <input type="date" class="form-control" datepicker-popup ng-model="dt" is-open="opened" min-date="minDate" max-date="'2015-06-22'" datepicker-options="dateOptions" date-disabled="disabled(date, mode)" ng-required="true" close-text="Close" />
+              <input type="date" class="form-control" datepicker-popup ng-model="dt" is-open="opened" min-date="minDate" max-date="'2020-06-22'" datepicker-options="dateOptions" date-disabled="disabled(date, mode)" ng-required="true" close-text="Close" />
               <span class="input-group-btn">
                 <button type="button" class="btn btn-default" ng-click="open($event)"><i class="glyphicon glyphicon-calendar"></i></button>
               </span>