Component type of icon prop type support

[ngxiaoyi]

Hi there,

If this component plugin depends on the font - FontAwesome which comes from the repository : react-native-vector-icons. Why not support component type for the 'icon' prop directly?

eg:

import ItemCell from 'react-native-item-cell';
import Icon from 'react-native-vector-icons/FontAwesome';
<ItemCell
icon={<Icon name="rocket"/>}
>
Item
</ItemCell>

#just a feature wanted

[ngxiaoyi]

Filed a PR: #21

Please have a review and fell free to handle it. Thanks