Update to 2.4.1

Fix for https://github.com/boxen/puppet-mongodb/issues/6 @gregimba

However, there's a pretty big bug in 2.4.1 for Ruby: https://jira.mongodb.org/browse/SERVER-8799

So, not sure if this should wait until the 2.4.2 release on the 8th April?

Your call :+1: