add xscheduler
add Host#scheduler_path filed
add field for Host#scheduler_path
parse job_id for xscheduler
add validation on Host#scheduler_type
get host_parameters when saved

- when Host#scheduler_type is updated to "xscheduler", it retrieves host_parameters using 'xsub -t' command.
implement parse_jobid_from_submit_command
removed Host#scheduler_path field
refactoring: move scheduler_log_file_paths to SchedulerWrapper
send job_parameters for xscheduler
refactoring: SchedulerWrapper.scheduler_log_file_paths
set scheduler_work_dir for xscheduler
SSHUtil.directory? method
download_recursive downloads not only directory but file
bug fix for xscheduler
disable template and host_parameters fields
trivial refactoring
run job from work_dir

- job is executed at run_dir
  - job script must not have cd #{run_id};
  - however, for manual_submission, cd #{run_id} is necessary.
  - therefore, 'if' statement to detect manual_submission is inserted
- scheduler log files are located at work_base_dir (not work_dir)
  - so add options to print scheduelr logs to work_base_dir
spec maintenance
add test for xsub