I'm trying to apply a google font to my Material-UI react project, but can't seem to get it to take. I'm using mui 0.14.2.

My `index.html` font load:
`<link href='https://fonts.googleapis.com/css?family=PT+Sans:400,700' rel='stylesheet' type='text/css'>`

My component where I apply the theme:

```
import ThemeManager from 'material-ui/lib/styles/theme-manager';
import LightRawTheme from 'material-ui/lib/styles/raw-themes/light-raw-theme';

const App = React.createClass({

    childContextTypes: {
        muiTheme: React.PropTypes.object,
    },
    getChildContext: function() {
        return {
            muiTheme: ThemeManager.modifyRawThemeFontFamily(ThemeManager.getMuiTheme(LightRawTheme), 'PT Sans, sans-serif')
        }
    },

...etc etc

}

```