Initiator update

• Main branch changed from bash to python.

• An optional variable initiator has been added.
  It can be set to print out who should be responsible for this run. This is especially useful when the workflow was started by another workflow through a bot.

Bugfix

Fixed bug where message wouldn't send if only one job failed.

Bug fixes and readme updates.

Fixed a bug when message is send if there are no failed jobs.
Now the action does nothing if all tracked jobs are completed successfully.

Cosmetic & funcional update

Action now supports multiple failed jobs.
Messages to Google Chat are now sent as Cards.