LPS-38029 send the message before importing/exporting so that I know what I am currently exporting/importing
LPS-38029 send the model name in the message
LPS-38029 provide the total count in the backend (not only the maps with classes)
LPS-38029 Use different constants for export and import (from Constants.*)
LPS-38029 missing css class
LPS-38029 display progress bar in the front end
LPS-38029 BackgroundTaskStatus can be null under some circumstances
LPS-38029 the backend seems to return negative or 0 values for the total in several moments of the process
LPS-38029 the counters may be null at some points of the process too