Fix #438 - don't use Unix pipes for our commands, use node pipes

This fixes `npm start` and `npm test` so you don't need to use a pipe at all.  It also fixes a bug in habitat, where you can't overwrite a variable in your `env` with something in the environment.
This is wrong because when you are doing this it simply override the whole `process.env` for that process (or whatever the right term for this running command).

The right way to do this (I might be wrong, but tested and working as expected) is to set process.env for both of `LOG_LEVEL` and `NODE_ENV`.

```
  process.env.LOG_LEVEL = 'fatal';
  process.env.NODE_ENV = 'development';
```