Set the following compiler defaults:
```
"target": "es6",
"module": "commonjs",
"moduleResolution": "node",
"sourceMap": true,
```
Which allows us to not even include a tsconfig.json file. If one is
present, `ts-node` will use its options, but the above settings will
override any settings in a local tsconfig.json file. This means if you
want full control over the target, you'll need to go back to the raw
tsc workflow where you explicitly build ahead of time.
