Improve notary startup exception handling

When there's an exception on notary service startup the logs first show a reflection exception which hides the underlying cause:

{{
[ERROR] 2019-06-10T17:28:03,749Z [main] internal.NodeStartupLogging.invoke - Exception during node startup [errorCode=h96akz, moreInformationAt=https://errors.corda.net/ENT/5.0-SNAPSHOT/h96akz] {}
java.lang.reflect.InvocationTargetException: null
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[?:1.8.0_202]
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
..
}}

This exception should be ignored and only the cause should be logged.