Updating ToolTasklet to allo MRv2 jobs to fail

MRv1 jobs run with the JobClient which throws an exception when they fail. MRv2 Job class returns a boolean to indicate success instead of throwing an exception. The existing ToolTasklet does not allow MRv2 jobs to fail the tasklet.

Hadoop tools should be using exit codes for success/failure so I pulled in the SystemProcessExitCodeMapper which will allow MRv2 tools to fail with exit codes and MRv1 jobs will still fail when errors are thrown.