# adding arc.coffee to be able to create simple arc representations

here's a patch that adds support to build simple gauge-arc representation. I've also updated the main.html to include 2 of these samples:

```
<d3-chart height="320" class="span6 simple-arc1">
  <d3-arc inner-radius="0.5"  data="{{ {percentVal:60, text:'60%'}  }}" label="text" amount="percentVal" transition="bounce" transition-duration="1000"></d3-arc>
</d3-chart>
<d3-chart height="320" class="span6 simple-arc2">
  <d3-arc inner-radius="0.5"  data="{{ {percentVal:90, text:'90%'}  }}" label="text" amount="percentVal"></d3-arc>
</d3-chart>
```