Fixed hanging on windows when there is no manifest

`findroot()` was getting into an infinite loop on windows, because this would never end:

```js
while (!exists(join(path, 'component.json')) && '/' != path) {
  path = dirname(path);
}
```

as windows root is not `/`.

At first I've tried using regexp, but than figured the path splitting approach would be more robust as there might be different path types, like `\\NETWORK\dir` and what not...
I've run too many times into a situation where you can't predict which separator the path is using. Often it uses both -.-

In this case the `cwd` should be consistent with `path.sep`, but the regex also handles duplicate separators like `/some//dir` (also shouldn't happen, but I wouldn't put my hand into fire for that), and network paths `\\NETWORK\dir`.

But yeah, `cwd.split(sep)` should work in most of the cases. If you don't care about reasons above I'll change it :)