Initial implementation of login and registration with fake backend for future testing

Also introduced flex-layout

src/app/account/auth.guard.ts

@@ -0,0 +1,21 @@
+import { Injectable } from '@angular/core';
+import { Router, CanActivate, ActivatedRouteSnapshot, RouterStateSnapshot } from '@angular/router';
+import { AccountService } from './account.service';
+
+@Injectable({providedIn: 'root'})
+export class AuthGuard implements CanActivate {
+  constructor(private router: Router,
+              private accountService: AccountService) { }
+
+  canActivate(route: ActivatedRouteSnapshot, state: RouterStateSnapshot): boolean {
+    const user = this.accountService.userValue;
+
+    if (user) {
+      return true;
+    }
+
+    this.router.navigate(['/login'], {queryParams: {returnURL: state.url}});
+    return false;
+  }
+}
+