setThresholds doesn't do anything

If I run the following code:

```javascript
mpr121.setThresholds(200, 190)
.then(function() {
mpr121.on('touch', function(pin) {
console.log(`Touch on ${pin}`);
});
});
```

then it doesn't matter what I set the two thresholds to, it will be just as sensitive as the defaults.

If I go into the library and change the defaults (12 and 6) to the numbers I want, then the thresholds actually change.

Start at the setThresholds entry point and compare how its arguments are handled with the library defaults of 12 and 6. Reproduce the provided JavaScript example, then verify that changing the arguments alters touch sensitivity rather than requiring the defaults to be edited.

Written by the indexing model from the issue text.