Rollback source on non blocking TransformConnector failure

This pull request runs the runs the inverseOps on the source of the connector when the target connector errors. The use case is that you can set up a fast source like `MemorySource` with a non-blocking connector and your UI can update immediately but if the connector fails it will rollback those changes. 

I'm not sure if this is something you want, or the way you want to implement it, but I was wanting to play with the library a bit anyways and creating this PR helped me get much more familiar with it. :smile: