feat: add app shell (angular-material)

Add app shell built using angular-material and flex-layout. Refractor
code due to configuration changes.

Fixes #52

src/app/self-service/self-service.module.ts

@@ -3,14 +3,12 @@ import { CommonModule } from '@angular/common';
 
 import { UserManagementComponent } from './user-management/user-management.component';
 import { SelfServiceRoutingModule } from './self-service-routing.module';
-import { CoreModule } from '../../app/core';
 import { CreateUserComponent } from './create-user/create-user.component';
 import { ViewUserComponent } from './view-user/view-user.component';
 
 @NgModule({
   imports: [
     CommonModule,
-    CoreModule,
     SelfServiceRoutingModule
   ],
   declarations: [