Collect diagnostics information if Job fails while execution and make it available to users

[michaelschnyder]

Originally mentioned in #12, where a job throw a NotImplementedException but is basically applicable for and exceptions that are unhandled and turn the state to failed.

Usually there is some logging infrastructure available in the jobrun itself that would log this kind of execptions, how-ever, if logging or boostrapping fails, these possibility might not be available and the consumer has (besides the Windows Error Log) no chance to find the issue.

Suggestion:

• Provide an endpoint where log messages can be sent.
• Log these messages to the logfile of the server (with a context, if possible)