added EventImportFile worker file

Conflicts:
	spec/dummy/db/schema.rb
added user_encoding to EventImportFile

Conflicts:
	app/controllers/event_import_files_controller.rb
	spec/dummy/db/schema.rb
fixed creating tempfile
added user_encoding to EventImportFile

Conflicts:
	app/controllers/event_import_files_controller.rb
	app/models/event_import_file.rb
	spec/dummy/db/schema.rb