v0.1.0 feature release

Features:

• Improve state storage (#6)
• Display reference solution code in result (#13)
• Use quick_store gem to store user data (#15)
• Show course author for Github courses in the daigaku screen
• Add CLI command for updating courses (#16)
• Add CLI command for deleting courses (#18)
• Add ruby doc link markdown tags (#19)

Bugfixes:

• Prevent solution scaffold for courses' README.md (#2)
• Show appropriate shortcuts in top bars in the daigaku screen (#10)