add initial user model
add initial topic  model
add relationship between User and Topic model
add initial Post model
add relationship between Post, User and Topic model
add application scss file with the correct bootstrap configuration and initial layout
add homepage route and add yield method into the application layout
add signin layout
setting sign-layout to NEW action users controller
add bootstrap styles and change text in the user views
once the user is signed then is saved user name in the rails session and it is redirected to topics index view
update application layout: add box title and box main content
add action current_user in application controller
create the association between current user when the Topic is created
save user id instead user name in the rails session
add timestamp to Post Model
add timestamp to Topic Model and add two methods for know the post number for current Topic and the date of the last post
update the main content layout
change styles, text and add content_for(:sidebar) in Topic index view
loads all bootstrap javascripts