[BUG] There is no way to stop the task

[AlexPykavy]

Steps to reproduce:

• Run curl -v -d '{\"id\": \"44923378-ac56-4870-a64c-e97aad95a0db\", \"name\": \"myapp\", \"executable\": \"sleep\", \"args\": [\"infinity\"]}' http://localhost:8080/tasks in PowerShell
• Run curl -X DELETE http://localhost:8080/tasks/44923378-ac56-4870-a64c-e97aad95a0db

Expected behavior:

• The task with 44923378-ac56-4870-a64c-e97aad95a0db ID to be deleted

Actual behavior:

• An error because task.Process is nil

Possible solution:

• Store exec.Cmd in the Task structure instead of the os.Process