2.1.0

fix bugs

• take the cancel jobs into account
• remove several job status metrics
  I have no idea when I remove(export metrics as 0) these metrics
  • flink_job_status_created
  • flink_job_status_failing
  • flink_job_status_failed
  • flink_job_status_cancelling
  • flink_job_status_canceled
  • flink_job_status_finished
  • flink_job_status_restarting

improvements

• build with docker