[jwflicker]

The IBM bluemix mobile data service sounds like a good match: https://www.ng.bluemix.net/docs/#services/mobiledata/index.h...

"With the Mobile Cloud Services SDK, you can embed a special managed directory in your application. Any files that are stored in this managed directory can be monitored and synchronized. The application can share the contents of this managed directory by connecting to Mobile Data with the same application ID and user ID. By sharing the directory contents, different instances of an application can have synchronized copies of the files"