Adds remember_digest colum to User table
Creates method for remembering users
Adds method to check if current user is authenticated
Implements piersistent login
Adds ability to forget a user being logged in
Addresses user logging out in different tab or different browser
Adds 'Remember Me' checkbox to Login form
Implements remembers user if Remember Me checkbox marked
Adds tests for logging in with/out remember user
Adds tests for SessionsHelper