scancel job array ID parsing fixes

Previous logic would not recognize a job ID specification with a
  job array task ID of "*" (e.g. "123_*") to indicated all job
  array tasks.
Previous logic would stop any parsing after the closing bracket
  on a job array specification (e.g. "123_[4-6] 234" would not
  see the "234").
Improve logging of job ID specifications (i.e. use job array
  specification).