Make valid_header? handle MalformedCSVErrors (#85)

Author: Joe Marty

lib/csv_importer.rb

@@ -85,6 +85,9 @@ def valid_header?
     end
 
     header.valid?
+  rescue CSV::MalformedCSVError => e
+    @report = Report.new(status: :invalid_csv_file, parser_error: e.message)
+    false
   end
 
   # Run the import. Return a Report.