Create database for flashcards

- create flashcards.sql including table decks and cards
- input data from flashcards.sql to flashcards database
Add primary key to id of decks
View a list of decks and cards
Set id as serial and delete id in INSERT argument
Create a new deck
Update deck
Create a new card
Update without change
Update without change
Add play link on home page
Add play
Update flashcards game

- add play link to deck edit
- add view correct answer link when play game
- change user input to be case insensitive