Improve logging when workflow names are misconfigured

[stephaneey]

Issue #60 describes the problem. I went through the sample but renamed the workflow file for some reason. Instead of calling it workflow1.json (thus ending up with the following URL http://localhost:3500/v1.0/invoke/workflows/method/workflow1), I named it wf.json but didn't realize the URL should have been http://localhost:3500/v1.0/invoke/workflows/method/wf. Logging was enabled but nothing was reported other than getting a 400 (Bad Request) error code.

Ideally, for such issues:

• Some extra logging info should be available
• Instead of a 400 for this particular case, a 404 would be more appropriate since it didn't find the workflow1.

Best Regards