Added new optional argument to send errors with no exception

[phillip-haydon]

When errors are logged with .LogError or equivalent, with no Exception, the ASP.NET middleware picks up 500 errors and ships those off to Raygun, this is causing duplicate errors to be raised.

New parameter makes this opt in.

[QuantumNightmare]

Setting this flag to false by default makes this a breaking change. From conversations with customers in the past, I know that logging an error message without an exception is a useful way in which the product gets used. If we really need this flag, then I think it should be true by default, making it opt-out.

I understand that this change was being made due to duplicate reports being sent from our web app (well, two different kinds of reports representing the same problem). But isn't that because we've wired up two different hooks for capturing request errors? Maybe the solution for us is to rethink how we've setup the logging in the app.