add Group model, add groups controller
Add groups into routing
Add index route of the groups controller, build basic page for groups
merge ch1.1.1
complete ch1.1.2
merge changes
complete ch1.1.3, create add form page
merge ch1.1.3
complete ch1.1.4, add group
merge ch1.1.4
complete ch1.1.5, add edit page
merge ch1.1.5
complete ch1.1.6
merge ch1.1.6
Add delete feature
merge ch1.1.7
merge ch1.1