I'd like to suggest you to consider adding shapeshift, just experiment with it for awhile or folks can use shapeshift directly. the exchanges won't be instant as it was with fortunejack on-site exchange service.
Shapeshift have lately added high fee for exchange, they are taking out around 0.002
BTC+ fees from every exchange this days if you try to exchange any coin to bitcoin. I have personally experienced this and i don't think integrating their api for exchange will be good idea.
Its better that fortunejack use their own holdings to provide this feature.