Created scaffold for Student
Added default param for student student params
Added presence validator for Student
Created scaffold for Task
Added not rescue for ActiveRecord::RecordNotFound
Added link to sign out
Protected students from the other users
Added authenticate user for TasksController
Added author field to Task field
Protected tasks from the other users
Created UserTag model
Created TaskUserTags table
Added inserting task's tags
Added tags in task show
Added tags in task index
Created scaffold for Test model
Added authenticate user for TestsController
Protected tests from the other users
Created tasks_students table
Added method by_tags for TasksController