Multiple commands in one file break Sketch
Given a command file `test.js` containing:

```
export function foo(){}
export function bar(){}
```

the output will be:

```
Object.defineProperty(exports, '__esModule', { value: true });

function foo() {}
function bar() {}

exports.foo = foo;
exports.bar = bar;
```

However, Sketch doesn't have an `exports` variable, so this fails. The problem doesn't happen when using `export default` because the result compiles to `var onRun`. This means that it isn't possible to hold multiple commands in a single file without some hackery. To work around it, one can do this:

```
var foo = function (){}
var bar = function (){}

export default function(){
  foo, bar
}
```

which compiles to:

```
var foo = function () {};
var bar = function () {};
var onRun = function () {
  foo, bar;
};
```

onRun can be ignored now that `foo` and `bar` are accessible. However, it must be included to ensure something is compiled (the file will be empty otherwise) and the references to `foo` and `bar` inside it trick the compiler into thinking they're needed, thus including them.