Issue: Fixed logout error and other problems (#12)

client/src/app/app-routing.module.ts

client/src/app/app.component.html

client/src/app/app.component.ts

client/src/app/authentication/auth.service.ts

client/src/app/posts/post-details/post-details.component.ts

client/src/app/posts/post-form/post-form.component.ts

...rc/app/posts/post-thumbnail/post-thumbnail.component.html

...rc/app/users/user-login-form/user-login-form.component.ts

client/src/app/users/user-logout/user-logout.component.html

client/src/app/users/user-logout/user-logout.component.scss

...t/src/app/users/user-logout/user-logout.component.spec.ts

client/src/app/users/user-logout/user-logout.component.ts

client/src/app/users/user.module.ts