This is a similar issue to Bug 787534. To create a snapshot revision you either need to create the snapshot first and then update it with the revision or possibly create it at the same time as the snapshot. However to do this you need to include the Snapshot object in the SnapshotRevision and then add a collection of revisions to the snapshot. So when this gets marshaled to JSON it causes a recursion error due to each object having a reference to each other.