Function output differs from accepted inputs

[WhatsARanjit]

https://github.com/WhatsARanjit/puppet-node_manager/blob/master/lib/puppet/provider/node_group/https.rb#L30

I've decidedly replaced environment_trumps with override_environment to follow what the PE Console showed at the time. But the node_group() function presents the environment_trumps key, which presents incongruence.

Changing this would be a breaking change for anyone keying off of environment_trumps.