Fix indent of User.php
Add setPasswordAttribute : to make hash password.

Add method : setPasswordAttribute in `User.php`.
This method is make hash password whenever input password to form.
Change HaikUsersTableSeeder.php

This change is for setting dummy user to test hashing.
Run `db:seed` then create dummy user with hash password.
Add auth routes for /haik-admin

Modify `routes.php` for authentication.
If you access to path include `haik-admin` you need login,
and redirect to `/login`.
Add login.blade.php to set login form

`login.blade.php` is simple naked form page.
This view has 2 input fields : email and password.
Add SessionController.php

This controller has methods :

* login()

* logout()
Modify routes.php to connect SessionController

Add routing to `/login` and `/logout`.
These routes connect SessinController's action.
Add validation in SessionController->login

Set validation to login form.
Use MessageBag class in SessionController.
If login failed, redirect to `/login` and flash error message.
This validation care about resend input data when reload page.
Not resend input data when reload page.

* Use MessageBag

* Set validation

* Add error message in login.blade.php

* Avoid resend input data when reload page
Merge pull request #18 from toiee/user-authentication

Add user authentication function