Pull Request for Issue 410 (DirectServiceClient causing issues in ServiceRunner)

Hi,

This is a proposed workaround for [Issue 410](https://github.com/ServiceStack/ServiceStack/issues/410).  

I'm not sure if using Service (and thus ServiceRunner), leaving DirectServiceClient unable to ever satisfy the condition in [ServiceRunner.Process](https://github.com/connectassist/ServiceStack/pull/new/master#L0R187) to call ExecuteOneWay is a problem.

Please let me know if I can address anything further.

Many thanks,

Carl


*Commit:*
Changed ServiceRunner to stop DirectServiceClient causing exceptions from null IRequestContext when using Service over ServiceBase<TRequest>

Updated the Services used in IntegrationTests.Tests.WebServicesTests to
inherit Service instead of ServiceBase<TRequest> along with the change.
Tests still pass.