Remove configure.createbus

Please review

Don't pull this until we have pulled https://github.com/Particular/NServiceBus/pull/2320 and rebased this one.
I wonder if there is benefit in instead of passing an instance of ConfigurationBuilder you pass a T that implements ConfigurationBuilder ?
So in essence a bootstrap class. 
So a user can create their own base bootstrap that derives from ConfigurationBuilder and then share it across projects.