BuildingBlocks as pseudo "Web Components"

**Note**
* BB `CSS` are not changed at all.
* During build time `bb-` tags are replaced with their template.
* For testing purpose i added `bb-header` and `bb-subheader`
* No performance issue, because we don't really touch the app.
* **This is not working on desktop yet!**

**Structure**
* All web components are stored in `shared/components`
* Each component can be stored in a separate file. eg: `shared/components/header.html`
* Here how a component looks like: 

```html
<element name="bb-tagname" attrs="attr1,attr2,attr3">
  <template>
    <!-- Stuff here -->
    <!-- you can use <content></content> to append content of the component -->
    Hello {{attr1}}
    <content></content>
  </template>
</element>
```

**Usage**
```html
<body>
  <bb-tagname attr1="val1">Hello World</bb-tagname>
</body>
```

**How to create a component**

Just create a new `.html` file in `shared/components`, using the structure describe above and that's it, you can use your component.

`bb-tagname` can be whatever you want but it needs a `-` somewhere.

> We use `handlebar` for templating stuff. ([more info here](http://handlebarsjs.com/))