Feature Add: Title as HTML code instead of string

I would like to be able to add an icon, or a clickable span, to the title of the gauge, like in the example below:

```
<just-gage id="test1" class="someClass" min=0 max=100 value=42 title="Title <i class="fa fa-pencil"></i>"</just-gage>
```

-or-

```
<just-gage id="test1" class="someClass" min=0 max=100 value=42 title="<span ng-click="myFunction( )">Click the Title</span>"</just-gage>
```
