[FT] Add plunk generator

### Here is my [ui.bootstrap plunker](https://github.com/angular-ui/bootstrap/blob/gh-pages/assets/plunker.js) fork for various modules.

What it looks like ;
```html
<div class="span12" ng-controller="PlunkerCtrl"
  ng-init="
    vendor_css = ['http://.../style.css'];
    vendor_js  = ['http://.../script.js'];
  "
>
  <div class="pull-right">
    <button class="btn btn-info" id="plunk-btn" 
    ng-click="edit('1.0.7', 'UI.ModuleName', 'ui-repo-name')">
    <i class="icon-edit icon-white"></i> Edit in plunker
  </button>
  </div>

  <tabset>
    <tab heading="Markup">
      <div plunker-content="markup">
        <pre class="prettyprint">
          [HTML HERE]
        </pre>
      </div>
    </tab>
    <tab heading="JavaScript">
      <div plunker-content="javascript">
        <pre class="prettyprint">a
          [JS HERE]
        </pre>
      </div>
    </tab>
    <tab heading="CSS">
      <div plunker-content="css">
        <pre class="prettyprint">
          [CSS HERE]
        </pre>
      </div>
    </tab>
  </tabset>
</div>
```

I didn't change a lot of things.

#### The important part is this one :

```html
<div class="span12" ng-controller="PlunkerCtrl"
  ng-init="
    vendor_css = ['http://.../style.css'];
    vendor_js  = ['http://.../script.js'];
  "
>
  <div class="pull-right">
    <button class="btn btn-info" id="plunk-btn" 
    ng-click="edit('1.0.7', 'UI.ModuleName', 'ui-repo-name')">
    [...]
```
Where `ng-init` allow you to inject css files in the plunk header and javascript files at the end of the body :

 - **vendor_css** : the css files dependencies 
 - **vendor_js** : the javascript files dependencies 

Then, the `edit` function takes as argument
 1. **ngVersion** : the angular version you want in the demo (here v1.0.7)
 2. **moduleName** : the name of the module. 
 2. **repoName** : the name of the repository. 

More generally the tabs are optional. For now you can only have only one of each. 

I'll use this directive in some module demo so you have some examples.

Close #9