Don't sync tiny worklog entries

[zerok]

It looks like JIRA doesn't like worklog entries that are tiny. At least with an entry having only one second, the following error was received from the server:

{
  "errorMessages": ["Worklog must not be null."],
  "errors": {
    "timeLogged": "You must indicate the time spent working."
  }
}

I'm assuming that limit is around 10 seconds. For now it will probably be enough to just not synchronise worklog entries shorter than these 10 seconds.