Initial commit of changes from kleijn: - Removed HandleUserCancellingImport: FileImporter should not decide on its own how to handle Canceled actions. Consequently removed the messages that are generated by these handles - Added logic to the importers: Cancelling is not possible when putting data on the data model. Action will always execute when it is in this stage - Added branching paths in the activity: Import() returns false when it has failed or is cancelled Note: failing tests will be fixed in following commits Related to Issue [WTI-490]