remove has_secure_password instead of using devise
remove the excess flash msg
remove authorise before_action in application controller
use user_signed_in? to judge is user login
adjust the image and user_nav
remove the new user in users index page
change Signed in/out to Logged in/out
rails g devise:views
change the routes for that sign_in to login and sign_out to logout
rails g migration add_username_to_users username
display username instead of name in users page
login in with username instead of email
use uesrname as authentication key instead of email
add username text field in sign_up page
add username text field in edit profile page
add permitted_parameters for devise controller
add before_action authenticate_user! except show and index in news page