Numeric input answer close

Please check out my changes. They have to do with the numeric input with multiplie answers. In the current implementation, if you go to an answer and type a single character and then delete it, the whole answer gets deleted. It can be pretty counter intuitive so I set up an explicit UI trash button for getting rid of answers you don't like. Please check over my work and please feel free to recommend changes to the UI or code, I will be more than happy to make any changes!

Thanks!
I love writing this kind of thing using ES 6 arrow functions: `() => this.onTrashAnswer(i)`