show full lookup path somewhere on missing dependecy

@xenoterracide commented on [Sat Jul 30 2016](https://github.com/aurelia/framework/issues/506)

**I'm submitting a feature request**
- **Library Version:**
1.0.1

```
% uname -a && node -v && npm -v && google-chrome-stable --version
Linux slave-vi 4.6.4-1-ARCH #1 SMP PREEMPT Mon Jul 11 19:12:32 CEST 2016 x86_64 GNU/Linux
v6.3.1
3.10.3
Google Chrome 52.0.2743.82
```
- **Language:**
all | TypeScript X.X | ESNext

**Current behavior:**

```
vendor-bundle.js:3675 Uncaught TypeError: h.load is not a function
vendor-bundle.js:1335 Unhandled rejection Error: Failed loading required CSS file: material.blue-red.min.css
at fixupCSSUrls (http://localhost:9000/scripts/vendor-bundle.js:23247:13)
at http://localhost:9000/scripts/vendor-bundle.js:23286:16
From previous event:
at CSSResource.load (http://localhost:9000/scripts/vendor-bundle.js:23285:10)
at ResourceDescription.load (http://localhost:9000/scripts/vendor-bundle.js:18906:28)
at ResourceModule.load (http://localhost:9000/scripts/vendor-bundle.js:18855:37)
at http://localhost:9000/scripts/vendor-bundle.js:19216:43
From previous event:
at ViewEngine.importViewResources (http://localhost:9000/scripts/vendor-bundle.js:19185:52)
at ViewEngine.loadTemplateResources (http://localhost:9000/scripts/vendor-bundle.js:19155:19)
at http://localhost:9000/scripts/vendor-bundle.js:19103:41
From previous event:
at ViewEngine.loadViewFactory (http://localhost:9000/scripts/vendor-bundle.js:19087:67)
at ConventionalViewStrategy.loadViewFactory (http://localhost:9000/scripts/vendor-bundle.js:16507:25)
at HtmlBehaviorResource.load (http://localhost:9000/scripts/vendor-bundle.js:19840:29)
at http://localhost:9000/scripts/vendor-bundle.js:20373:18
From previous event:
at CompositionEngine.createController (http://localhost:9000/scripts/vendor-bundle.js:20361:71)
at CompositionEngine._createControllerAndSwap (http://localhost:9000/scripts/vendor-bundle.js:20340:19)
at CompositionEngine.compose (http://localhost:9000/scripts/vendor-bundle.js:20420:21)
at TemplatingEngine.compose (http://localhost:9000/scripts/vendor-bundle.js:20684:38)
at Aurelia.setRoot (http://localhost:9000/scripts/vendor-bundle.js:10275:21)
at http://localhost:9000/scripts/app-bundle.js:55:59
From previous event:
at Object.configure (http://localhost:9000/scripts/app-bundle.js:55:25)
at http://localhost:9000/scripts/vendor-bundle.js:9148:29
From previous event:
at config (http://localhost:9000/scripts/vendor-bundle.js:9147:48)
at handleApp (http://localhost:9000/scripts/vendor-bundle.js:9138:12)
at http://localhost:9000/scripts/vendor-bundle.js:9167:13
From previous event:
at http://localhost:9000/scripts/vendor-bundle.js:9165:40
From previous event:
at http://localhost:9000/scripts/vendor-bundle.js:9164:29
From previous event:
at run (http://localhost:9000/scripts/vendor-bundle.js:9160:26)
at Object. (http://localhost:9000/scripts/vendor-bundle.js:9187:3)
at Object.execCb (http://localhost:9000/scripts/vendor-bundle.js:3683:299)
at Object.check (http://localhost:9000/scripts/vendor-bundle.js:3672:50)
at Object.enable (http://localhost:9000/scripts/vendor-bundle.js:3677:58)
at Object.enable (http://localhost:9000/scripts/vendor-bundle.js:3681:433)
at Object. (http://localhost:9000/scripts/vendor-bundle.js:3676:436)
at http://localhost:9000/scripts/vendor-bundle.js:3661:140
at y (http://localhost:9000/scripts/vendor-bundle.js:3660:207)
at Object.enable (http://localhost:9000/scripts/vendor-bundle.js:3675:469)
at Object.init (http://localhost:9000/scripts/vendor-bundle.js:3670:154)
at http://localhost:9000/scripts/vendor-bundle.js:3680:308
```
- **What is the motivation / use case for changing the behavior?**

It's obvious to me that this is because I've misdefined paths in `aurelia.json` but it's not clear to me exactly what I've done wrong, printing out the path that it's trying to open server side would be helpful.

Also more complete documentation of `aurelia.json` would be nice.