Use Ctrl+Shift as my Slate keybinding

After all the suffering I went through to fire the Hyper cluster on
those two keys, Ryan Keener pointed out I could just, you know, have
Slate respond to Ctrl+Shift.

This fixes probably the stupidest programming mistake I've made in five years.
Add 'DOM' to my personal spelling dictionary

It's a phrase web programmers get to use a lot.