relative paths in the resources property of a dependency

**I'm submitting a feature request**

* **Library Version:**
0.28.0

**Please tell us about your environment:**
* **Operating System:**
OSX 10.x|Linux (distro)|Windows [7|8|8.1|10]

* **Node Version:**
6.2.0

* **NPM Version:**
3.8.9

* **Browser:**
all | Chrome XX | Firefox XX | Edge XX | IE XX | Safari XX | Mobile Chrome XX | Android X.X Web Browser | iOS XX Safari | iOS XX UIWebView | iOS XX WKWebView

* **Language:**
all | TypeScript X.X | ESNext

**Current behavior:**
When using the following config:

```
{
"name": "datatables",
"path": "../node_modules/datatables/media/js",
"main": "jquery.dataTables.min",
"resources": [
"../css/jquery.dataTables.min.css"
]
}
```

It does not bundle the CSS file, resulting in the following 404:

`GET http://localhost:9000/node_modules/datatables/media/js/media/css/jquery.dataTables.bootstrap.min.css 404 (Not Found)`

**Expected/desired behavior:**

It should either bundle the file correctly, or if this is not possible it should give an error message during build