Tracing the reason of task launch failure

[hanahmily]

Which version of Elastic-Job do you using?

2.1.2

Which feature you expected

When the task fails to launch, the framework gets a TASK_ERROR message. But this message does not contain the specific reasons for failure, it is difficult to locate the problem.

So add some details of the failure to the message body, such as exception message or java stack information, can solve this problems