#2457 - Swap Helvetica Neue with Ideal Sans

**WIP** Fixes #2457

Things I’ve noticed by just swapping references to Helvetica with Ideal:

1. The baseline in Ideal Sans is higher than in Helvetiva, so there’s a larger gap in some buttons.
2. The strokes are thicker in Ideal for the same font-weights compared to Helvetica

![idealvshel](https://cloud.githubusercontent.com/assets/65468/3457068/13495da0-01f5-11e4-9e52-56f00668ffa6.png)

So we may have to individually tweak buttons to they look symmetric. As for the strokes we may want to use Ideal Sans Semibold instead of Bold (though this is just my personal preference).