Fixes for cookbook

[nicolemah99]

• Remove logger and tag STREAM from log function

  • new log function echo "$1" >&2

• /meters/sel375/commons.sh

  • handle_sigint()
  • mark_event_incomplete()
  • validate_download()

• Add trap fail SIGINT to data_pipeline.sh, this calls exit 1

  • Add trap handle_sigint to download.sh to handle moving current event to .incomplete

• mark_event_incomplete()

  • moves current_eventid directory to .incomplete#
  • rotates .incomplete directories after 5 .incompletedirectories

• Change variable names

  • otdev_download_timestamp --> download_timestamp
  • meter_download_timestamp --> event_timestamp

• Removed all echo messages

• Updated log messages

• Replace exit 1 checks with fail()

• Update README.md