[ADF-1088] Task Header in TaskDetails component shows Assignee but is not editable (#2176)

* added translate keyword for assignee header

* changed people-search component to change the header according to filter type

* changed tash-header component to make assignee clickable

* imlemented people-search component to assign the task to new user

* added handler for assign task to new user

* added testcase for assign task to user

* changed mdl textbox to angular material

* changed button to md and fixed issues in testcase after changed md

* changed property for people-search component

* added ng-content selector to pass header text and action button text  and removed property from people-search component

* added no_error_schema to fix testcase issue in people component

* fixed no-task-details component test case bug

* added people-search component in read me

demo-shell-ng2/app/components/activiti/activiti-demo.component.html

@@ -72,6 +72,7 @@
                             (formCompleted)="onFormCompleted($event)"
                             (formContentClicked)="onFormContentClick($event)"
                             (taskCreated)="onTaskCreated($event)"
+                            (assignTask)="onAssignTask()"
                             (taskDeleted)="onTaskDeleted($event)">
                         </activiti-task-details>
                         <hr>

demo-shell-ng2/app/components/activiti/activiti-demo.component.ts

@@ -382,4 +382,9 @@ export class ActivitiDemoComponent implements AfterViewInit, OnDestroy, OnInit {
     isTaskCompleted(): boolean {
         return this.activitidetails.isCompletedTask();
     }
+
+    onAssignTask() {
+        this.taskList.reload();
+        this.currentTaskId = null;
+    }
 }