Underlying process async

[Aaron-P]

Right now the underlying process of the importer interface is synchronous though the interface being used is async. It might be beneficial to make the process itself async, but I'm not sure how feasible it would be since EF DbContext is not thread safe. I don't think it would be an issue with the current setup, since we are creating and disposing of the contexts in each method call, but it might be better in terms of performance to use a shared context instead of going async.