Report learning/recall interval in verbal learning task

[noah10]

We should add two fields to the verbal-learning-learning output: One that reports the total delay between the end of verbal-learning-learning and the start of verbal-learning-recall (which starts after the countdown timer is done) and one that reports how long the countdown timer ran for. I'll leave it up to you, @Floozutter, as to whether this is better done in the baseline/client code or in the JSON->CSV code.

[noah10]

Per @maramather , we are going to use the moment when someone presses the space bar after reading the first instruction screen in verbal-learning-recall as the moment that verbal-learning-recall begins.

[noah10]

Also per @maramather , we do not need to report how long the countdown timer ran for.