Adds mailer to users
Adds link to forgot password page
Adds password_reset action to the sessions controller and adds a route
Adds reset_password view
Completes the actions in the sessions controller for password reset
Adds password_reset_token and password_reset_sent_at columns to the users table
Adds send_password_reset method to User model
Adds send_reset_password method to user mailer
Adds configuration to action mailer for development environment. Adds reset password mailer view
Adds configuration for action mailer to the production environment
Completes mailer for forgetting a password
Adds configuration for sendgrid and mailer
Sets up environment settings for mailer for the development and production