Create videos controller with the 2 basic methods: show and show_all
Create model User and Video and migrate db
Add views to show and show_all
Add basic routes to root, show and show_all
Add validation for title and youtube_id on model Video, and instance method full_name to model User. App ready to start, as expected to be in branch 'e-start' of makersquare/metube-cohort3.