initial i18n messages for loading and error components

src/app/shared/loading/loading.component.ts

@@ -1,12 +1,36 @@
-import { Component, Input } from '@angular/core';
+import { Component, Input, OnDestroy, OnInit } from '@angular/core';
+
+import { TranslateService } from '@ngx-translate/core';
+
+import { Subscription } from 'rxjs/Subscription';
 
 @Component({
   selector: 'ds-loading',
   styleUrls: ['./loading.component.scss'],
   templateUrl: './loading.component.html'
 })
-export class LoadingComponent {
+export class LoadingComponent implements OnDestroy, OnInit {
 
-  @Input() message = 'Loading...';
+  @Input() message: string;
+
+  private subscription: Subscription;
+
+  constructor(private translate: TranslateService) {
+
+  }
+
+  ngOnInit() {
+    if (this.message === undefined) {
+      this.subscription = this.translate.get('loading.default').subscribe((message: string) => {
+        this.message = message;
+      });
+    }
+  }
+
+  ngOnDestroy() {
+    if (this.subscription !== undefined) {
+      this.subscription.unsubscribe();
+    }
+  }
 
 }