Creates the database tables.

def init_db():
    """Creates the database tables."""
    with closing(connect_db()) as db:
        db.cursor().execute("DROP TABLE IF EXISTS entries")
        db.cursor().execute(
            """
            CREATE TABLE entries (
                id INTEGER PRIMARY KEY AUTOINCREMENT,
                title TEXT NOT NULL,
                text TEXT NOT NULL
            )
            """
        )
        db.commit()