add new migrations to change the database
Add Gem 'cancan'
add new column 'role'
add new entries
add config for cancan-gem
cancan ability-class
new models
get current_user for CanCan
show the last 5 Campaign-Histories on Dashboard
part-3: compare the platfors and budget to create new Campaign-History
new function to check user role
add validaton and relation to platforms
update Gemfile.lock and schema.rb