Fixing isAnswerSlotValid in Flash cards

[chrischang]

…all the time and fixing typo and descriptions

[logicminds]

I just fixed this myself using

function isAnswerSlotValid(intent) {
    var answerSlotFilled = intent.slots && intent.slots.Answer && intent.slots.Answer.value;
    var answerSlotIsInt = answerSlotFilled && !isNaN(parseInt(intent.slots.Answer.value));
    return answerSlotIsInt
}