Don't abort the migration if the simulation fails

We think aborting the migration will generate more headaches to system
administrators, who will have to manually check and fix every invalid
record before anything can be migrated.

lib/tasks/globalize.rake

@@ -41,7 +41,7 @@ namespace :globalize do
         begin
           record.save!
         rescue ActiveRecord::RecordInvalid
-          logger.error "Failed to save #{model_class} with id #{record.id}"
+          logger.warn "Failed to save #{model_class} with id #{record.id}"
           @errored = true
         end
       end
@@ -68,17 +68,20 @@ namespace :globalize do
     end
 
     if errored?
-      logger.error "Simulation failed! Please check the errors and solve them before proceeding."
-      raise "Simulation failed!"
+      logger.warn "Some database records will not be migrated"
     else
       logger.info "Migrate data simulation ended successfully"
     end
   end
 
   desc "Migrates existing data to translation tables"
-  task migrate_data: :simulate_migrate_data do
+  task migrate_data: :environment do
     logger.info "Starting data migration"
     migrate_data
     logger.info "Finished data migration"
+
+    if errored?
+      logger.warn "Some database records couldn't be migrated; please check the log messages"
+    end
   end
 end