Quiz session and builder objects

[caioertai]

Closes nothing... We changed the way quiz sessions are going to be handled for now.

• Lint Gemfile
• Add rspec Gem and install
• Add User#pending_quiz(section)
• Add tests for QuizSessionBuilder
• Add #build return
• Add building new QuizSession case for QuizSessionBuilder#build
• Refactor implements test for QuizSessionBuilder
• Fix context for users on QuizSessionBuilder specs
• Update question to use prompt instead of content
• Update syntax of yaml files
• Update redirect path from quiz sessions form
• Update model associations with relevant dependent destroys
• SQ above
• YAML import script
• Add optional to quiz question answer
• Get errors on quiz session and quiz question model if not fully answered
• Add full error wrapper to list radio buttons on quiz
• Checking valid for all quiz questions
• Add quiz questions behavior
• Remove quiz session to quiz
• Remove anwer from quiz sessions
• Create quiz question answer
• Rename quiz session builder to quiz builder
• Quiz session with answer as belongs to
• Fixed yaml
• added explanations to backend
• Add explanation to quiz reports
• Remove quiz report from section menu
• Quiz session rewiring
• Move quiz report methods to QuizSession
• Move quiz report partials to quiz sessions views
• Move course Sessions controller to Quiz::Sessions
• Building quiz with QuizSession
• Fix not answered quiz question style and checking all before marking invalid