Feature: Json schema for aurelia.json

**I'm submitting a feature request**

* **Library Version:**
all

**Please tell us about your environment:**
* **Operating System:**
all

* **Language:**
all

**Current behavior:**
Currently when working with the file `aurelia.json` its pretty hard to know what each property and setting is about and on top of that if you misstype something you won't know what is wrong.

**Expected/desired behavior:**
I'd like to add a json-schema describing the aurelia.json file

* **What is the expected behavior?**
* Have a schema file hosted on https://github.com/schemastore/schemastore/
* Have an example aurelia.json file hosted inside the aurelia cli repository
* Reference that example via the json schema's id property using rawgit

* **What is the motivation / use case for changing the behavior?**
* Full intellisense for aurelia.json props and keys
* Inline documentation directly in your editor
* Links to the aurelia.io docs
* Validation inside your editor of choice

* **Examples**
I've started working on that feature in this repository https://github.com/zewa666/aurelia-json-schema
Also take a look at below animated gifs for what this all is about. Its showing how json validation can work in VSCode

*** Inline documentation ***

*** Inline Validation ***