refractor: login module (#283)

* Refractor components.
* Shift language and footer component to shared module.
* Replace mat-icons by font-awesome icons.
* Add comments.

Fixes #284

src/app/core/alert.service.ts

@@ -1,17 +1,22 @@
 import { Injectable, EventEmitter } from '@angular/core';
 
+export interface Alert {
+  type: string;
+  message: string;
+}
+
 @Injectable({
   providedIn: 'root'
 })
 export class AlertService {
 
-  public alertEvent: EventEmitter<any>;
+  public alertEvent: EventEmitter<Alert>;
 
   constructor() {
     this.alertEvent = new EventEmitter();
   }
 
-  alert(alertEvent: any) {
+  alert(alertEvent: Alert) {
     this.alertEvent.emit(alertEvent);
   }
 

src/app/core/index.ts

@@ -11,3 +11,4 @@ export * from './http/error-handler.interceptor';
 export * from './route.service';
 export * from './route-reusable-strategy';
 export * from './logger.service';
+export * from './alert.service';