Implement StatisticsModel class

StatisticsModel class represents model which contains data - statistics logs list with current telemetry item and respective JSON data. This model could be utilized by UI controls like combo boxes, text browsers, JSON treeviews, etc and by service classes like QScheduler,  QNetworkManager to send left behind data to backend.

• data() returns
  • current telemetry
  • archived (from log)
• rowCount() method
• filter model by telemetry level:
  • current telemetry
  • archived (from log)
• reselModel() method to reload data
• Doxygen documentation for the class and methods
• Add TransferedRole to data() => isTranferred(json) method
• A-dd method to return not transferred files list or similar-