Add HomeController and index view

* generate HomeController and spec
* add index view and action
* configure root route
Add User model

* generate User model with password hash and salt
* migrate User table
Add bcrypt-ruby gem

* install bcrypt-ruby gem
* write encrypt_password method on User model
Add User sign-up and authentication

* generate UserController
* add user new/show views and actions
* configure user routes
* add form_for on user sign-up page
* write authenticate method on UsersController
Add user log-in and log-out

* add SessionsController
* add sessions new view and sessions actions
* add form_tag log-in to sessions#new
Merge pull request #1 from nkabrown/bcrypt

Bcrypt